Add a set of tests using a fake implementation of PDF.js'
PDFViewerApplication interface.

The initial set of tests simulate a nice born-digital PDF in which the
text layer of the PDF contains one <div> per line. In future we can
easily extend this to emulate the kind of structure that would be seen
when working with eg. an OCR-ed PDF

Remove the "-app" suffix from Gulp tasks

Remove AnnotationUIController

This is a holdover from when the Hypothesis service front-end and client
application lived in the same repository and the "-app" suffix was used
to indicate client-specific tasks. Removing this gives the tasks more
obvious names - "build", "build-js", "test" etc.

All of the functionality in this module is either unused or duplicated
elsewhere:

 * The $scope.{selectedAnnotations, focusedAnnotations,
   selectedAnnotationsCount} properties were unused.

   Note that there is a very similarly named `selectedAnnotationCount`
   scope property defined in `WidgetController` which _is_ used

 * The ANNOTATION_DELETED event handler duplicated another one in
   root-thread.js

This function expects an ID, not an Annotation

Add a set of HTML anchoring tests with expected failures

Fix formatting changes made via toolbar buttons not persisting

Add application state debugging utility

Add a set of tests which check that Ranges within a DOM tree are
correctly 'described' as selectors and then successfully converted back to
Range objects by anchoring.

The tests are derived from the suite of test cases collected for the
Annotator project at
https://github.com/openannotation/annotator/blob/v1.2.x/test/spec/range_spec.coffee

These tests found failures in describing ranges with position and quote
selectors in many cases and with a range selector in one case. The test
lists and checks these expected failures.

When making formatting changes to the text of an annotation with the
toolbar button without subsequently making a manual edit before clicking
Preview or Save, the onEditText() callback was never triggered and so
the unsaved changes were reverted when exiting edit mode.

This happened because onEditText() was only fired in response to the
'input' event which only occurs in response to programmatic, not manual
changes to the input's value.

Fixes #147

This adds a debug utility which prints the application state before and
after each action to the console when `window.debug` is set to a truthy
value.

Move session state to the Redux store

Fix prevent default override

In current versions of PDF.js, the `RenderingStates` enum is no longer
exported as a global, and the export method appears to be dependent on
the build configuration.

Since `RenderingStates` is a trivial enum, this commit fixes the problem
by just reproducing it in `pdfjs-rendering-states.js`.

Use Node v6.2 on Travis

This keeps things consistent with the version of Node used by h:

    https://github.com/hypothesis/h/commit/cc71f6c571829344e1f50a05b33504a2d42725d4

This fixes an error when trying to load the Hypothesis client on the
stream or standalone annotation pages, caused by both the stream app and
the sidebar app trying to set up a 'Discovery' server for annotation
'guests' to connect to.

With this change, only the sidebar app will set up a Discovery server
and hence it is now possible to annotate the stream and standalone
annotation pages.

Upgrade raven node package

Fix scrolling to direct-linked annotations

Fix adder from affecting website's height on load

The FrameSync service introduced in 55093ebb emitted an
ANNOTATIONS_SYNCED event which unintentionally had a different type for
the `tags` argument than the previous code (`string[]`, instead of
`Array<{tag:string}>`)

This commit updates the code in WidgetController to expect `tags`
to be of type `string[]`.

Fixes #129

Move the session state out of the "session" service and into the Redux
store.

This enables logic in reducers and action creators to access the
logged-in user, list of groups and active feature flags.

Remove crossframe service and simplify communication with connected frames

Now that AnnotationSync is no longer used in the sidebar app, we can
remove all of the handlers for events and messages arriving through the
channel which are not needed by the page itself.

Previously the communication between the sidebar and host frame was
implemented by a shared AnnotationSync class, with a 'crossframe'
service which abstracted the event bus on each side.

This design however assumed that both sides wanted to listen to
the same messages and react to them in similar ways. This is not
the case, especially given the change to use Redux for state
management in the sidebar app.

This commit replaces the crossframe service and AnnotationSync class
with a new 'frameSync' service which implements only the event
listeners and sidebar -> page RPC calls that are actually needed.

As a result, local annotation tags for annotations loaded via the API
can now be assigned by the reducer in the Redux store, making this
easier to test and getting us another step closer to making Annotation
objects immutable in the sidebar app.

Yesterday a brief issue occurred where the server reported an incorrect
(too high) total number of results for a URL due to the search index
being out of date. Once the client reached the end of the actually
available results, it made queries to the search endpoint which returned
an empty result set but had a `total` figure implying that there should
be more pages. The client then ended up polling the server indefinitely
for more results.

This commit defensively makes the client stop fetching more result pages
if the current page is empty.

When calculating the count of pending updates that is used to determine
whether to show the 'Apply Updates' icon or not, count deletions.

In addition to changing the count calculation itself, this also requires
that pending deletions are discarded for annotations that are not
currently loaded. Such notifications may be received because the
deletion may have happened in an un-focused group. Unlike create/update
notifications, no group information is included in the notification
itself so we look up the ID in the local store.