Small Bug fixes

test_images_oneserver.py: tierDownClass done by the base class
	the remove method was wrong anyway
test_server_personality: "Error" undefined, let the exception propagate
test_container_sync.py: missing import: time

Change-Id: I69a1311c07d9472587b7407ba0cbc55d276f3531
Removes use of nose.tools.raises

Removes uses of nose.tools.raises and replaces it with
assertRaises. This makes it consistent with how expected
exceptions are handled in other tempest tests and is part of the
process of removing dependencies on nose.

For the files that were altered use of attr(type='negative') were
also removed. These are not used as the tests already handle the
expected failures by catching the exception (formerly by using
@nose.tools.raises decorators). These need to removed eventually
as the nose.plugins.atttrib.attr decorators are replaced by the
testtools attr decorators which will remove the final
dependencies on nose (but nosetests will still be able to be
used, it just won't be required).

Change-Id: Id8a86da283fd16dd5a907be28d442c23c17cb35c
Merge "Small Bug fixes"