Adding switch to build.cmd to skip KRE install
Use ITypeActivator to construct transports in TransportManager
Remove constructors that take IServiceProvider from *MessageBus
Replace ConfigurationManager with SignalROptions

- This follows the ASP.NET vNext configuration conventions
Remove the HubDispatcherMiddleware

- We can reuse the PersistentConnectionMiddleware instead now that
  we don't have to pass through a different configuration type.