Forever Frame JS client now runs received payloads through custom JSON if configured:
- Capture the original JSON for the connection
- In FF transport, if current JSON !== original JSON (custom set) then stringify using original JSON and parse using custom JSON
- Added JS unit tests to cover new behavior
- Corrected hubs.js version in samples project
- #2945
Address review feedback & added samples code:
- #2945
Fix version in hubs.js
Server changes to support long-polling keep alives

#1781
Support long-polling keep alives on the JS client

#1781
Support long-polling keep alives on the .NET client

#1781
Disable keep alive checks if there is a LongPollDelay

- Ensure we don't timeout the connection because there is a delay between
  poll requests
- Disable keep alive checks  if the server didn't send back the LongPollDelay
  as part of the response to /negotiate. That indicates the server is running
  an older version of SignalR that doesn't send long polling keep alives.

#1781
Start testing the long-polling transport in KeepAliveFacts

#1781
Fix deadlock in ForeverTransport.ProcessMessages

- Since disposer.Set sometimes blocks waiting on InitializeTcs,
  ensure disposer.Set isn't called until InitializeTcs has completed.
NullMethodDescriptor now lists potential matching methods
#981
Inconsistent casing in NullMethodDescriptor fixed
#981
Updated tests to expect NullMethodDescriptor to list overloads

#981
fixed spelling of Error_NoDependencyResolver in owin extensions
Stop the connection heartbeat after the JS test has completed

- Leaving the heartbeat active caused an FFConnectFacts test to fail since
  verifyLastActive was unexpectedly getting invoked by the heartbeat
Update tests so they pass in TestSwarm

- Use relative paths to establish connections
- Don't assert the long polling transport is monitoring keep alives if
  XHRs have no onprogress event
Made the backoff time for Service Bus configurable

#2954
Adding support for WP81 and WPA81 targets.
TooStrict - removing "use strict" from the output js files. Fixes #2964.
Clear reconnectAttemptTimeout in serverSentEvents.stop

#2925
#2757 Support flowing causation error to disconnect error handler in JS client