pub/sub messages with non-single bulk values should be usable; to avoid breaking the API, we unroll such messages into N discreet messages to the specified channel
adds connection-id tracking (used for test, but we want this later anyway - we've been meaning to add this for a while)
This PR encorporates https://github.com/StackExchange/StackExchange.Redis/commit/df805be6ccb977c4b5fc5dc9a60174219c9564b5 - I did a stoopid and failed to branch
This change fixes #2507: