Delay authentication timeout on scope updates

Fix two issues with the authentication timeouts.

- Fix #1284, the regression causing resets to always occur, introduced
  by e4f32116fe5f266e2030a666f5cc912b6b3df308
- Flash a message when the reset happens. Close #1280
- Increased the timeout to five minutes, as per suggestion by @dwhly
Open socket after session, not delay

It makes a lot more sense to start the websocket connection as soon as
the session is loaded, rather than using an arbitrary delay time of
five seconds.
Reset the websocket after auth changes

Fix #1286
Merge pull request #1287 from hypothesis/websocket-tweaks

WebSocket tweaks
Merge pull request #1285 from hypothesis/1280-auth-form-timeout

Delay authentication timeout on scope updates
Add and register the debugtoolbar package

This now renders stack traces in the browser rather than the vauge and
unhelpful "Internal Server Error" message. This is a godsend when
trying to debug issues with SCSS files.
Merge pull request #1293 from hypothesis/debugtoolbar

Add and register the debugtoolbar package
Restore default view to 'Screen'

As a part of the fix for #1231 in commit
https://github.com/hypothesis/h/commit/f66448fc3b2d1e07cbb491db73367b4b69e5f9a6
the default view was change to 'Document' from 'Screen'
but the annotations were not loaded into the sidebar as supposed
for 'Document' view, because the applyView was called before
the annotations were loaded.

Since it'd take effort to correctly implement Document view update
when the store loads new annotations, it is feasible to return
to the original 'Screen' view, which works well, because
views are planned to be refined, maybe redesigned.

Fix #1276
Merge pull request #1295 from hypothesis/1276-load-annotations-to-sidebar

Restore default view to 'Screen'
Refactor API code to use annotator-store flaskless