* Implement new attributes for labels
* Include correct API header in all Labels calls
* Add integration tests for Create and Update methods for labels
* Use improved labels API in observable client
* found even more endpoints that need the preview header!
* RemoveFromIssue actually returns the list of remaining labels rather than null. This change should be source compatible but not binary compatible
* Implement new labels search method in SearchClient
* Implement reactive client SearchLabels
* Improve documentation for label search methods
* more comment tidy up
