Removed the SendOnly property support for MVC Endpoints.

Currently there are some challenges with the SendOnly option in the MVCEndpoint. The SendOnly option is available only for MVCEndpoints and not for NSB Endpoints.

The following issues arise that the current version doesn't correctly address:
1. What should happen, if you make the MVC endpoint publish an event and the endpoint is marked Send Only? - Give out a recommendation to not do that? Block out the publish operation?
2. What should happen if you try to deploy a handler to the SendOnly endpoint.
3. For the SignalR integration, should we not have the option show up if its a SendOnly endpoint or throw a different recommendation?

At the moment, this is broken. Code might compile but the endpoint may not have a queue and might fail to receive events if expected to handle events.

Until the above requirements are addressed, it doesn't make sense for this option.