Fixed duplicate messages from being received in scaleout.
- Use backplane generated timestamp to determine what to do when
  the cursor is bigger than the max cursor on that particular node.
- Extended the cursor id format to support timestamps as ticks in hex.
- Renamed CreationTime to ServerCreationTime and made CreationTime the
  backplane creation time
- Added stress test to verify the duplicate behavior when flip flopping between nodes.

#1973
Added unit tests for cursor parsing.
- Fail scaleout subscription if timestamp is missing.
- Fixed broken functional test.
Use HasValue for nullable instead of comparing to null.
- Added test for verify we throw if cursor is missing the timestamp.
Added unit tests to verify the behavior of the ScaleoutStore.
- Fixed issue with updating the minMapping id
Use MaxMapping for checking if we've reset.
Removed timestamp from cursors.
- Always opt for missing messages instead of getting all on that node when
  cursor is bigger than max.
- Removed code from each backplane that gets the server time.