Bug 485939 - Remove touchpoint leaves .p2bu file

Discarding the backup store does not remove backups created via
renameInPlace.  These should be cleaned up in removeBackups.

Of course there should be tests for this so I updated the existing tests
to include testing for proper clean after calling discard.

Change-Id: I6c0a8adf4a2e04e33d70a6a66d908e82380f0085
Signed-off-by: Ed Merks <ed.merks@gmail.com>
4 files changed