Built out the Server payload compression pieces.  Copied from the 1234 branch on SignalR/SignalR

- Also copied custom SignalR source (compiled from 1637/1638 issues on SignalR source).
Added sample project to test the compression addon
Removed the TaskHelpers and added the TaskAsyncHelper from SignalR source to maintain consistency for the addon.
Moved the CompressPayloads call from the HubPipeline extensions to the DependencyResolver extensions.

- Also created a CompressionBase that can be accessed by the DependencyResolver.Compression()
- CompressionBase also now has the CompressPayloads function
Added a new connection that is mapped via the CompressPayloads method to return contracts
Changed the namespace on the server to be SignalR.Compression.Server

- Also added the system.web assemblies to the server so we can MapConnections