* Need a separate set of primitives to handle messaging
* Using Channels (not Pipelines!) to provide the data flow for messaging
* All transports are now "message" based transports
* Added an adaptor to convert message-based transports to serve
streaming endpoints
- Changed IHubConnectionContext and friends to be generic.
- Hub by default is Hub<IClientProxy>. We'll enable dynamic and arbitrary TClients in another commit.