Updated log message for keep alive monitoring

Resolves #1084
Make it possible to use Forever Frame when requested.

- Instead of failing due to window.EventSource is supported, a log message sent that better transport methods are available.
Changed reconnecting to disconnecting
This pull should close #1057

Changed back to the initial check of window.EventSource, but with different log message
Changed log message for not supporting FF when SSE is supported.
Merge branch 'release' into dev
Update message loops sample to detect all duplicate messages then stop connection when new message is not duplicate instead of running forever
Merge pull request #2849 from DNIDNL/bug-1057

Change log message when Forever Frame is skipped in browsers that support SSE.
Merge pull request #2843 from thecodejunkie/keep-alive-error-message-update

JS client keep alive starting log message update
DumpingDisconnect.Net

Removing handling Disconnect message in the .NET Client as the server no longer sends Disconnect messages.
DumpingDisconnect.JS

Removing handling Disconnect message in the .JS client as the server no longer sends Disconnect messages.
TransportAbortHandlerIsMovingOn - removing transport abort handler
(We wish him luck in /dev/null)

Fixes workitems #3067 and #3102
Update Katana (Microsoft.Owin) dependencies from 2.0.1 to 2.1.0
Prevent MessageBus from hanging forever in the second call to Dispose
Transport!YouAreFinished! - generalizing AbortSent flag

The transport is not in a usable state if either the abort request is sent or the transport was disposed. When in this state the transport should no longer be used. Before it was guarded by the AbortSent flag but the abort request does not necessarily have to be sent so the AbortSent was replaced with a new Finished flag which is set to true if either the Abort method was called or the transport was disposed.
Welcome?BackTransportAbortHandler - reverting TransportAbortHandler removal

We found that removing TransportAbortHandler caused a few issues and there might be more we did not find. Reverting change to avoid breaks.
Stop processing messages before ending the WebSocketFunc Task

- This should prevent ObjectDisposedExceptions from WindowsIdentity
  in OnDisconnected
WIP