call notifications:

- basic impl. of call notification (WiP)
- close ws connection on page unload
- user is automatically signed out on page unload
- notification views
- live incoming call notification
- dedicated ws events for notifications
- wording, whitespacing
- better error notifications for sign{in,out}
- added tests for incoming call offer
- moved signin/signout test helpers to the root scope
- keep on siplifying tests
- call accept/deny events
- update users list when a ws connection is closed
- clear notifications on signout
merge with master
cs & code legibility
added a weitFor() test helper
fixed waitFor check interval wasn't cleared on timeout
Merge pull request #37 from n1k0/call-notifications

Call notifications