Add a new set of unit tests that test more cases.

Rename options to config in annotator

There are two reasons for renaming the `options` object to `config`:

**First**, it's more consistent. The file that creates this object is
called `config.js`, and the function that creates the object is called
`configFrom()`, and yet the object ends up getting called `options` (but
you have to look in another file, `main.js`, to find this out).

`config` is also used elsewhere as the name for the main configuration
object, for example in Pyramid/h, in the client docs ("Configuring the
Client", "configuration settings") and public API
(`class="js-hypothesis-config"` scripts and `window.hypothesisConfig()`
functions), etc.

These "options" that the `src/annotator/` code reads from the host page
also end up getting renamed to `hostPageConfig` when they get passed
over in to the `src/sidebar/` code.

**Second**, it's more unique. There are a number of other objects in the
`src/annotator/` code that are called options, sometimes the main
options object and another local options object are even used in the
same function. There's no other objects called config.

This makes it easier to grep for uses of this function.

Rename the `config()` function that creates the `options` object to
`configFrom()`.

This is because I want to rename the `options` object to `config` in a
future commit, so I need the `config()` function to be called something
else.

I think `configFrom(window)` is also clearer (that this is a function
that returns a `config` object created from the given window) than
`config(window)` (which could be read as configuring the window, for
example).

Improve the `src/annotator/config.js` unit tests

The main change is to make the tests much more detailed by adding more
unit tests describing and testing more of the code's behaviour. But
also:

* Remove some test fakes which implemented non-trivial fake behaviour:
  `fakeScriptConfig`, `fakeQuerySelector`, `fakeWindowBase`. Just use
  simple stubs instead.

* Make each test test just one thing (previously many of the tests for
  one part of the code could fail if another part of `config.js` was broken).

* Isolate the `config.js` unit tests from `src/shared/settings.js` and
  `extract-annotation-query.js`. Previously the `config.js` tests could
  fail if `settings.js` or `extract-annotation-query.js` were broken,
  and implementation details of `settings.js` and `extract-annotation-query.js`
  were coded into the `config.js` tests.

* Fix an issue with one test that if it failed a `window.document` would
  be left modified

A few followup fixes to "Allow publishers to customize user menu links followup"

Prevent Adder toolbar from inheriting CSS property values from host page

The adder toolbar uses Shadow DOM or `!important` to prevent CSS rules
in the host page from directly affecting the styling of the toolbar.

However even inside Shadow DOM elements can still inherit CSS property
values from parent elements [1].

This commit fixes that problem for current browsers (except Edge [2]) by
using `all: initial` on the Adder's root element.

[1] See https://github.com/w3c/webcomponents/issues/314
[2] http://caniuse.com/#feat=css-all

Fixes #382

Add config option to show highlights only when sidebar is open

Update jQuery to current version & slim build

Instead of two different js-* classes. Simplifies the JavaScript code.

According to our CSS guidelines, use js-* CSS classes as handles for
JavaScript to find HTML elements.

Allow publishers to customize log out, profile and help links

Convert the "showHighlights" option from a boolean into an enum with
three values: "always", "never" and "whenSidebarOpen". When the last
mode is selected, highlights will only be shown when the sidebar is
open.

Stubbing `getComputedStyle` in the pointer events test resulted in the
test failing after the jQuery update in the previous commit because the
`css(..)` jQ method used by that test depends on `getComputedStyle`
internally.

Use `serviceConfig()` everywhere

Update our horrifically old jQuery build which included workarounds for
browsers we no longer support to the current stable version of jQuery.

Also switch to using the slim build which excludes features we don't
use.

This reduces the size of the minified jQuery bundle from 96KB to 68KB.

Always use `serviceConfig()` instead of accessing `settings.services`
directly.

If the user is logged in to a third-party account and the host page has
provided an `onHelpRequest` callback function, then call this function
when the _Help_ button in the sidebar's login menu is clicked, instead
of doing the button's normal behavior.

Enable partner sites to customize the behavior of the user profile link
in the sidebar's login menu.

The current behavior of this link is:

* If the user is logged out it doesn't show
* If the user is logged in to a first-party account it does show, and
  links to their https://hypothes.is/users/<username> page
* If the user is logged in to a third-party account then it does show,
  and displays their username, but it is just an unclickable `<span>`
  not a link

This commit changes it so that if the user is logged in to a third-party
account and the host page has provided an `onProfileRequest` callback
function, then the profile link will be clickable and clicking it will
call this callback function instead of linking to a hypothes.is user
page.

If the user is logged in to a third-party account but no
`onProfileRequest` function has been provided, then the link will be
shown unclickable as before.

The current behavior of the log out button in the sidebar is:

* If the user is logged out it doesn't show
* If the user is logged in to a first-party account it does show
* If the user is logged in to a third-party account it **does not** show

Change the log out button to show when the user is logged in to a
third-party account **and the host page has provided an onLogoutRequest
callback function**. When clicked the log out button will call this
callback function, instead of doing the normal (first-party) log out
procedure.

If the user is logged in to a third-party account and no
`onLogoutRequest` callback function has been provided, then the log out
button will not be shown (as before).

When a on*Request callback function is provided by the host page (for
example onLogoutRequest) add a corresponding onLogoutRequestProvided
boolean to the settings object.

This is because the on*Request functions don't get passed from the host
page context into the sidebar code, because functions aren't JSON
stringifiable, so the sidebar code has no way of knowing whether or not
a callback function was provided.

We're going to be adding code to the sidebar that does need to know
this, so add on*RequestProvided settings to tell it.

Reorganize the tests according to the components (the different items in
the login menu) instead of by context.

Instead of:

    when a first party user is logged in
      it shows the profile, account settings, help and log out buttons
    when a third party user is logged in
      it only shows the profile button (but disabled) and the help button username
    etc

We now have:

    describe: the profile button
      when the user is logged out
        it does not show
      when a first party user is logged in
        it shows the enabled profile button
      when a third party user is logged in
        it shows the enabled profile button
      etc

    describe: the log out button
      etc
    etc

This will make the tests easier to write as we're going to be adding
more complex behavior to some of the buttons, both logic about when the
buttons do and don't show and are enabled or disabled, and logic about
what happens when a button is clicked. It'll be easier to manager if all
the tests for each button are grouped together. eorganize tests by
component

There's no need for this function to use `new` or `this`.

Some minor docstring fixes

Show an error message to the user when getting or refreshing an OAuth access token fails