channelPrefix disables Keyspace Notifications

[zivillian]

Using a connectionString with a channelPrefix options seems to disable all Keyspace Notifications.

As far as I can tell, all Pub/Sub Messages are checked against the prefix - if any is configured (RawResult.cs#L80). Since the Keyspace and Keyevent messages have a prefix of __keyspace@ and __keyevent@, they will always be discarded if any channelPrefix is used on the ConnectionMultiplexer.

[NickCraver]

This is being worked on in #813 :)