Use Hub<T> for strongly typed client methods

[bcanseco]

http://stackoverflow.com/a/26555776/6609109

AC:

• [ ] All hub classes use strongly typed client methods.
  • May require changes to the HubResource class.

[bcanseco]

Will not be possible due to the way HubResource instances handle comms for hubs. Might change after #11.

[bcanseco]

This is now possible in alpha2 - can upgrade and implement. https://blogs.msdn.microsoft.com/webdev/2017/10/09/announcing-signalr-for-asp-net-core-alpha-2/