Code review comment for lp:~cbehrens/nova/rpc-kombu

Restores most of the original interfaces with only slight changes to satisfy work Zed is doing.

This keeps carrot as the default for now. There were slight modifications to carrot done to support an interface change... as well as to handle changes to FLAG values regarding rabbit retries.

To use kombu, use --rpc_backend=nova.rpc.impl_kombu

Moved rpc tests into a common class, so that tests for the default module as well as tests for carrot and kombu can all be shared. There's a test for fanout for kombu that is SKIP'd because the 'memory' transport built into kombu that I'm using when FLAGS.fake_rabbit=True seems to be buggy. When I run the test against a real rabbit server (FLAGS.fake_rabbit=False), that test passes fine.

Please give the tests a run. They all pass for me. zedas said he might have seen a failure somewhere in his scrollback, but I'm unable to see one.