Added ability to respond to synch queries for Redis

@anpete Both materialized and non-materialized queries now working. 

TODO: add same ability for asynch queries
I'm still finding a lot of problems with the ConnectionMultiplexer. Only way to debug was to have already started server - otherwise it frequently died as soon as it tried to connect - which meant I couldn't debug anything after that. Will update this when I address https://github.com/aspnet/EntityFramework/issues/487