More robust mocking of nova conductor

Update the nova notifier test to use the fake RPC implementation
to avoid hangs more completely.

Also update the test to mock out the entire conductor API object
in the manager created by the test, instead of mocking individual
methods.

Change-Id: I741a609bd3ddfeb302d39b1c61a4b6896de2bf47
Signed-off-by: Doug Hellmann <doug.hellmann@dreamhost.com>
Merge "More robust mocking of nova conductor"