Rename the subscribe message to consume to reflect that we're now going to force clients into a pull model instead of a push model. This decision was made to fix an issue with the push model whereby the possibility existed of getting a message with a higher vector clock before a message with a lower clock. If a client crashed during this delivery, it would mistakenly request messages greater than the larger clock, and miss the message with the lower clock value.
Add TestIsSelf to the ring tests.