Bundle the clean theme related config options into the theme = 'clean…

Some of the config settings don't work well with the clean theme. Some others don't work
without the clean theme. It would be better to remove the following config options and
have each of these elements tied to the over all 'theme' of the sidebar for consistency:
disableToolbarCloseBtn
disableToolbarMinimizeBtn
disableToolbarHighlightsBtn
disableToolbarNewNoteBtn
disableBucketBar
enableSidebarDropShadow
enableCleanOnboardingTheme

See https://github.com/hypothesis/product-backlog/issues/380

Show the shorter version of the empty annotations/notes message when …

Don’t link tags to activity pages on eLife

The stream page was replaced by the search page. Update some old
references to the stream in the tests.

Tag search pages aren't supported for third-party annotations in h, so
don't link to them from the client.

Fixes https://github.com/hypothesis/client/issues/616

Fix out of date account-id fake

The fakeAccountID object in annotation-test.js was out of date: it
contained only a username() function that annotation.js doesn't call
anymore, and did not contain the isThirdPartyUser() function that
annotation.js _does_ call.

The tests were still passing because annotation.js's isThirdPartyUser()
method, which call's account-id's isThirdPartyUser(), wasn't tested. Add
an integration test for this method to catch this.

I've also moved fakeAccountID out into its own variable with a name,
instead of it just being an anonymous object literal. This makes it more
explicit. For example if account-id's API is changed, you can just grep
the code for fakeAccountID to find all the fakes that need to be
updated.

Move the annotationComponent() function into the describe() scope nearer
to where it's actually used. This puts the code nearer to where it's
used and is going to be useful in the next commit when it's going to be
changed to make use of one of the fake variables in that scope.

Don't show page share button on eLife pages

Remove traces of persona.js

persona.js was renamed to account-id.js.

persona.js was moved to account-id.js in
35f1a03d but this proxyquire call is
still patching persona.js not account-id.js.

Don't show the "Share this page" button in the top-right of the sidebar
on pages, such as eLife's, that have both an embedded Hypothesis client
and a services config including their own `authority` string.

The "Share this page" button is a Via link, and Via doesn't work with
pages using a third-party authority config.

Fixes https://github.com/hypothesis/client/issues/615

Show the shorter version of the empty annotations/notes message when the sidebar tutorial is displayed
and the new note button is enabled.

Fixes https://github.com/hypothesis/client/issues/610

Don't show share dialog if no incontext link

If the annotation received from the API contains no incontext link (as
is the case with third-party annotations, for example) then don't render
the annotation share dialog that contains the incontext link.

Dont hyperlink annotation timestamps when the annotation has no href

If an annotation, as received from the API, doesn't have any html link
in the links object in the API response, then `vm.href` in
`timestamp.html` will be an empty string (due to the behaviour of the
`htmlLink` function in `annotation-header.js`).

When this happens render the annotation's timestamp as a `<span>` rather
than as an `<a>` with an `href` attribute that has no value.

I'm going to be making this template more complex, so extract it our
into a separate file first.

Rename account ID utility functions

Change button tag to span for the minimal onboarding look.

Extract OAuth client into a separate module

Remove `oauthEnabled` client config setting

Usage of this config setting was removed in
68e6524b.

The `OAuthClient` module creates the token responses so it makes sense
for the type definition to live there.

This simplifies the service implementation and the tests by separating
concerns better.

In order to make the `oauth-auth` service easier to follow and test,
split out the logic responsible for actually making requests to the
OAuth endpoints into a separate module.

The `oauth-client` module is also intended to be something that a third
party could fairly easily reuse or study for building their own client.

sidebar/filter/persona.js used to contain an Angular filter for use in
templates. However following several refactorings it now contains a
simple set of utility functions for parsing account IDs. This renames
the module accordingly and puts it alongside other utility function
modules.