Fix errors that occur when streams don't match cursors
- Reset cursors when the number of streams and cursors
  don't match.
- Added unit tests

#2024
Changed version to 1.1.1
Added test showing group removal not working (esp with longpolling)
- Updated test project to not include private copy of CountDownRange
  and OrderedCountDownRange.
Fixed issues with group token.
- Make sure group token is properly updated on changes
- Made diffset just detect changes in groups.
- Serialize group token even if groups are empty.
- Added tests for the new diffset.

#2040
Call AddEventCore from SetEventTopic.
- This will stop overriden methods from running. DefaultSubscription
  was incorrectly calling AddEventTopic during SetEventTopic.

#2040
Make diffset work better.
- Truly Detect changes and added unit tests
  to verify new changes.

#2040
Update ReleaseNotes.md
Merge branch 'release1.1'
Merge pull request #1 from SignalR/master

Pulling in changed from SignalR main project