Made some changes to service wire up and options

- Inline services into AddSignalR. This aligns with the pattern
most frameworks are using now and puts it all into one place.
- Remove IHubPipeline completely and replace it with an option on
HubOptions. HubOptions now exposes a stack of IHubPipelineModules.
- Added SignalROptionsSetup which has the default configuration for
SignalR.

/cc @DamianEdwards @halter73 
I think it would be fine to make this an IList. Once we actually generate the pipeline, the modules will effectively be aggregated into a stack, but I don't see any need to use a more restrictive collection than necessary for organizing the pipeline.