This is code motion with some small changes to make follow-on's
easier.
test_blockdevice_mbr.py is moved alongside the other tests. It is
modified slightly to use the standard base class and remove a lot of
repeated test setup; a fixture is used for the tempdir (so it doesn't
have to be torn-down, and is removed properly on error) and the partx
args are moved into the setUp() so each test doesn't have to create
it. No functional change. renamed test_mbr.py for shortness.
test_blockdevice_utils.py is merged with existing test_utils.py. No
change to the tests.
test_blockdevice.py is removed. It isn't doing anything currently; to
work it will need to take an approach based more on mocking of calls
that require elevated permissions. It's in history if we need it.
Change-Id: I87b1ea94afaaa0b44e6a57b9d073f95a63a04cf0
