This implements support and a test environment
in which the Hypothesis client can live reload
when scripts, styles etc. are changed.

Live reloading when scripts change currently requires
support from the hosting page.

There are two parts to this:

 - A server which serves test pages
   with the Hypothesis client embedded and notifies
   it when front-end assets (styles, scripts) are changed.

   Test pages are served at http://localhost:3000/<any path>
   by default.

 - A small client script which connects to the server and
   listens for notifications of asset changes.

   When styles change it will reload styles for the page.

   When scripts or Angular templates change it will send a
   request to the top-level page to reload.

   This enables reloading to work when changing
   both the sidebar app and Annotator code but also avoids
   the need to manually unload the existing Annotator instance
   before reloading.

CSP violation: admin confirm users delete

Which fixes a CSP violation, but it was also always the preferred
solution. This wasn't done in the first place as we didn't have any JS
bundle set up for admin, that exists now, so it's time to move the
confirmation dialog triggering into the proper place.

Rename postgres_read feature flag to postgres

In order to be able to execute specific JS code on certain admin pages.

So we get reports about JS errors in the admin bundle.

This is particularily important since we introduced a bug in the past
that didn't confirm the users delete form which could have led to
deleting users and all their data without a confirmation dialog.

Make client injection robust to pages that replace the URL fragment as they load

Display 'Show all N public annotations' message when there is a selection

Sites such as Medium and EBSCOHost modify the URL fragment as the page
loads, causing direct-link annotation ID fragments to be lost by the
time the app's init code runs.

When a tab's URL changes, extract the '#annotations' fragment and pass
it to the application as configuration info when the app is injected.
If the URL fragment is removed or replaced by client-side JS as the page
loads, the app will still get the original annotation ID that was
captured by the extension prior to the page load completing.

The direct-linked ID is remembered until the sidebar is successfully
injected, at which point it is cleared so that it is not re-used on the
next navigation within the tab.

Provide a way for the browser extension to pass config info to the app,
by running a content script which injects a <meta> tag into the page
with this form:

  <meta name="hypothesis-config" content="<JSON data>">

This configuration info is then merged with the result of the
hypothesisConfig() function, with the hypothesisConfig() function taking
priority.

When parsing the '#annotations' fragment, ignore any extra content
outside of the url-safe-base64 character set for annotation IDs.

This helps in cases where extra content has been appended to the URL
fragment after '#annotations:<ID>', before the client loads. This
happens at one point during loading of Medium.com pages for example.

Remove incontext links for replies

In the case when the selection has been set as a result of visiting a
direct-linked annotation, this makes it more obvious that there are
other annotations on the page to see.

Uri normalize unicode

Avoid showing 'Clear Selection' or 'Clear Search' buttons whilst loading

When loading annotations whilst a search query is active or selection is
present, avoid showing the 'Clear Search' or 'Clear Selection' buttons
until the search has actually completed and we know whether any
annotations match the query or selection.

This fixes the flash of the 'Clear Selection' button when viewing a
direct-linked annotation.

Fix broken loggedout CTA.

* Create a loggedout-message directive
* Move related html to separate template

https://trello.com/c/dR3qXaxx/257-add-explanatory-text-below-public-focused-annotation-when-logged-out

Preserve URL fragments when redirecting to PDF.js in extensions

Minor copy and style tweaks to the logged-out message

- We prefer "Hypothesis" in prose text to "Hypothes.is"
- Remove unwanted padding at the end of anchors.
- Say "sign in" rather than "log in," as we do everywhere else in the
  sidebar.
- Slight improvement to readability of call-to-action sentence by
  separating the "X or Y" clauses.
- Add a small gap between the two paragraphs.

Reintegrate annotation/document migration

Preserve selection when switching accounts

When visiting a direct-linked annotation (ie. #annotations:<id> is
present in the URL) we want to preserve the selection when the user
signs in, whether the annotation was private or in a group, in which
case they will need to sign in to see it, or public, in which case they
might need to sign in to reply.

Previously public direct-linked annotations became deselected when
signing in because they were unloaded when switching accounts, and this
fired the same ANNOTATION_DELETED event as when an annotation is
removed, which results in the annotation being removed from the
selection.

This commit enables the selection to be preserved by introducing a
different event within the app when annotations are unloaded vs.
deleted. When an annotation is unloaded, it is not removed from the
selection.

Fix a unicode warning

CSP Violation: form input onfocus

Merge pull request #3124 from hypothesis/sheetaluk/257-add-explanatory-text-below-public-focused-annotation-when-logged-out

Add message when user logged out and directed to an annotation.

When non-hypothesis users(or logged out users) are viewing a direct linked
annotation, we want to help them understand what they are looking at and
encourage them to sign up(or sign in).

Display a CTA message when:
* user is logged out
* user has landed on a DL
* there is a selection
* user has permissions to view the selection

Also,
* Add logo svg
* Update icomoon css
* Pull variables\.scss from 03cbef2

Fix the signature of NSQ error/exception handlers

Which fixes a CSP violation with having inline JavaScript.

Merge pull request #3146 from hypothesis/sheetaluk/294-as-a-user-i-want-to-be-able-to-find-out-who-is-a-member-of-a-group-i-m-in

Show list of group members in the group page.

Users want to see other users in the groups they belong to
and annotations each of these users have made and shared with a
group. This will help them decide how to share annotations with
their groups.

https://trello.com/c/rSUQLuos/294-as-a-user-i-want-to-be-able-to-find-out-who-is-a-member-of-a-group-i-m-in

List group memberships of user in admin interface

Use event constants consistently for events that are emitted
via $rootScope.

Convert AnnotationUI, AnnotationUISync from CoffeeScript to JS

Add Visual Studio Code project config file for JS

Merge pull request #3130 from hypothesis/sheetaluk/303-add-explanation-text-to-the-sharer-on-only-me-and-group-annotations

Add message to private and group annotations sharer.