Fix notification of comments and tips so that we keep track of failures

When something fails we record it as having been failed
Merge remote-tracking branch 'origin/master'

* origin/master:
  fixed a couple of notification bugs

Conflicts:
	globaleaks/models.py
Move Event class definition into plugins.base
Consume errors of the deferred list of the deferred list

If we do not do this and some of the deferreds fail they will result in an
unhandled error in Deferred.
Merge pull request #74 from hellais/fix/do_notify_refactor

Fix/do notify refactor