Thread model and UI improvements

Adds thread model/collection for managing conversation-level state, such
as unreadCounts, group membership, thread order, etc... plus various UI
improvements enabled by thread model, including an improved compose
flow, and thread-destroy button.

Adds Whisper.notify for presenting messages to the user in an orderly
fashion. Currently using a growl-style fade in/out effect.

Also some housekeeping:
Cut up views into separate files.
Partial fix for formatTimestamp.
Tweaked buttons and other styles.
Merge pull request #38 from liliakai/threads

Thread model and UI improvements
Redo registration process
Add human readable version of errors
One more tiny error refactor
Request new keys (largely untested)
Fix new function(){}() typo (thanks codedust on GitHub)
Few typos blocking registration
More typos from me being too tired
Save sessions in deviceObjects, test using fake_api, minor tweaks
Fix longstanding(?) attachment bug
Retry API, standardize <script> list
moved some chromium-specific code into chromium.js (using extension.navigator namespace)