Make Firefox gracefully abort when a tab is closed

- This change is only needed for cross-omain scenarios
- This does not work when the entire browser window is closed

#2400
Updated katana.
Fixed typo in abort connection log message.

#2404
Remove "groups token is missing log"
Correctly identify HubExceptions with null ErrorData on the clients

#2376
Updated HubException related tests to address code review comments

#2376
Modified connection.stop to no longer deffer itself until the page has loaded.

- It now unbinds the load event handler for the connection start.
- This allows for multiple starts/stops to occur during page load.
- This issue cannot be unit/functionally tested directly because it requires the page to be in the loading state.

#2189
Made it so stopping the connection will always unbind the "load" event if one has been bound.

#2189
Updated the self host package description.

#2384
sample to test pending callbacks
test SendToUser
Re-add obsolete OwinExtensions: MapHubs and MapConnection

#2242
Re-added a SystemWeb package to allow for a better update scenario.

- SignalR.Core will fail to update properly if updated individually.

#2242
Fixed test.
Updated copyright.
Fixed package building
- Added -nocache to the feed.
- Updated katana packages.
Fix race where PollingRequestHandler continues after Disconnect

- This causes an unobserved exception in the .NET client

#2405
Re-ordered when we clear private non-timeout based state.

- This way we can successfully reject connection deferrals.

#2189
Added a test to verify when we start->stop->start that all deferred's are rejected or resolved correctly.

#2189
Changes to middleware registration to run in specific iis pipeline stage.