closes #7371

closes #7370

closes #7192

closes #6340

closes #6257

closes #6005

Conflicts:
	Gemfile
	Gemfile.lock

  *bootstrap-dropdown
  *bootstrap-modal
  *bootstrap-popover
  *bootstrap-transition
  *bootstratp-twipsy
  *jquery-ui-1.8.9.custom.min.js
if we need the bootstrap files we should include them via the gem bootstrap-sass

The jquery.mentionsInput plugin upstream is no longer maintained.

- updates underscore to 1.5.2 and backbone to 1.1.0

backbone had some breaking changes:
- fix url/urlRoot handling in models & collections
- options are no longer attached to the view by default
- collections reset when 'fetch' is called, tell it to keep the existing
  models

other changes:
- fix some events triggering multiple times in connection with deleting
  a model
- use document fragments instead of an element array for stream entries
- adapt jasmine and cucumber specs to the changed code
  * no longer test the backbone router as part of our code
  * jasmine factory already returns model instances, no need to wrap
    that again

+ make some tests a little nicer