switch FLAGS.* = in tests to self.flags(...)

remove unused cases of FLAGS from tests
modified test.TestCase's flags() to allow multiple overrides
added missing license to test_rpc_amqp.py

nova/tests/test_rpc.py

@@ -20,13 +20,11 @@ Unit Tests for remote procedure calls using queue
 """
 
 from nova import context
-from nova import flags
 from nova import log as logging
 from nova import rpc
 from nova import test
 
 
-FLAGS = flags.FLAGS
 LOG = logging.getLogger('nova.tests.rpc')