Cleanup from business logic refactor

This patchset resolves a few minor nits including proper translation
of a couple strings in exceptions, order of addCleanup in
test_keystoneclient, a simple white-space change to make a line
more readable, and adding a bug reference to a comment.  All of these
changes are in response to comments on the deletion business logic
refactor that moved business logic from the controllers to the *_api
managers.

Change-Id: I2a446611a0fb91b946e986342ae5ede926b8dd44
bp: assignment-controller-first-class
Merge "Cleanup from business logic refactor"