OnConnectionSlow test for Long Polling

- Added new test for checking that OnConnectionSlow does not fire for Long Polling

#1960
Made modifications from code review

#1960
Code Review Changes

- Made modifications from Taylor's comments

#1960
Initial c++ client skeleton.
Removed bool from send callback.

Sends will be queued in the order they were called and callbacks
will fire in order.
Started fleshing out server sent events transport.
Moved some common logic into TransportHelper.
Fixed a name.
Only call start callback on initialized being received.
Added HttpBasedTransport to share code long polling logic.
Added initial LongPollingTransport.
Added basic reconnect logic to sse and cleaned a few things up.
Remove callback from Send api.
Added reconnect url logic to sse.
Enqueue sends in the HttpBasedTransport.
Fixed formatting
Added Casablanca library to the CPP Client

Rebasing to remove casablanca110.dll

Removed upgrade report
Added casablanca library

Changed NegotiateResponse to NegotiationResponse
Changed IHttpClient to http_client
Adding WebSocket Skeleton

-Added WebSocketTransport
-Changed some functions to return tasks
-Changed some string to string_t
Implementing SSE

- also modified some other files to reflect changes in definitions in IClientTransport
- added utility functions in TransportHelper