Scroll to login form when clicking sign in link

This fixes an issue that if the login form is already shown but the
iframe is taller than the window and scrolled down so that the form is
out of view, then clicking on Sign in would do nothing. With this fix,
clicking Sign in scrolls the iframe up to the login form.

Realtime notifications for pages with the same link

Namespaced NSQ

Simplify code

Some more cleanup / simplification about the "Refresh UX" PR.

Removed some dead code

Add an atom feed for /stream

Refresh welcome page

AppController listens to 'beforeAnnotationCreated'

By doing that it catches newly created annotations and clear the current
selection/search result for the newly created card to be visible.

Fix #1979

Sync annotation state after anchoring

It was never called when the anchoring was finished.
This code adds the missing sync.
It is required for show diff to work.

Fix #2041

Separate the Host service

.. from AnnotionUISync.

Earlier, the show/hide frame functionality was implemented as a
background functionality of the AnnotationUISync service,
and it was not directly available for the sidebar code.

This commit separated that functionality into a new service,
and exposes it over a public API.

The test have been updated accordingly, too.

Do angular magic differently

This commit changes how we trigger the refreshing
of the markdown previews in the editor.

It has to do with how angular apply / digest cycles
interwene and crash in some cases.

The change was suggested by @RawKStar77 here:

https://github.com/hypothesis/h/pull/2038#discussion_r26867418

Explicitly disallow implicit relative imports

Add tooltips on adder buttons.

Change text of the toolbar button to "New Note."

Use Lato as font for welcome page to make it visually consistant with our
website.

Require PyJWT>=1.0.0,<2.0.0

Replace flash service with angular-toastr

Add IE autodetect for dom-text-mapper Annotator plugin

JWT Bearer Tokens

Fix #2051

Autocomplete feature for tags

Introduce tagsService which will handle the necessary filtering of tags
and saving them into the local storage in an appropriate format.

s/Heroku/Docker/

Refresh UX