Adding keystone notification listener support

Notification listener processes only keystone project delete events.
It uses keystone project id to identify if related barbican resources are there
and deletes that project related barbican resources.

10/07/2014: Keep resolving rebase conflicts as this change is pending for a while.
Modified listener transaction logic as per related recent change in barbican.
Fixed missing patcher stop in few places which was causing failure in new tests.

Implements: blueprint consume-keystone-events

Change-Id: Iba7d50eb222edd43352ef82f629df2b3187c76ec
Delete usage-indications from the model docstrings

I removed some lines from the docstrings in the models due to them
indicating the usage of the function in other parts of the source. This
is not useful as the code could be refactored later, or other usage
could be given to these functions, and thus the comments would become
easily obsolete. Thus, this commit removes them.

Change-Id: I467c8c0a2d7d149e18d2aff87cafb23896bbbca7