Only close the response stream if ending the task completes the http request.
Set the stop flag when aborting the transport due to timeout.
#2180
Added tracking for the negotiate request so calling stop properly aborts the request.

- Without aborting the negotiate request starting and stopping in quick succession can cause multiple active ajax requests attempting to connect.

#2160
Added test to verify starting and stopping doesn't result in multiple client side connections.

- Also had to fix up some past tests that were not returning their ajax handles in replaced ajax functions.

#2160
Added test to verify hub event handlers are only triggered once per binding.

- This is a multi-purpose test to verify 3 bugs.

#2187
#2160
#2190
Addressed code review comments
Merge branch 'release' into dev

Conflicts:
	samples/Microsoft.AspNet.SignalR.LoadTestHarness/Scripts/jquery.signalR.js
	samples/Microsoft.AspNet.SignalR.Samples/Scripts/jquery.signalR.js
	samples/Microsoft.AspNet.SignalR.Samples/Scripts/jquery.signalR.min.js
	src/Microsoft.AspNet.SignalR.Client.JS/jquery.signalR.core.js
	tests/Microsoft.AspNet.SignalR.Client.JS.Tests/Scripts/jquery.signalR.js