Merge pull request #19 in SHRINE/shrine from feature/SHRINE-2145-add-an-optional-changes-since to develop

• commit 'eac4b3a8a8a573ecf7016c77c3103be3f20a61c7': (25 commits) Added some debug logging in case we need to diagnose in the field. Some improved error messages for SHRINE-2145 Added some logic to be sure that (if everything is working) spray won't give up on the request before the timeout response goes out for SHRINE-2145 Added a scheduled cleanup of the notification Map every 5 minutes. SHRINE-2145 Extracted QepQueryDbChangeNotifier into a singleton where other parts of SHRINE can trigger changes for SHRINE-2145 Added version and isComplete fields to ResultsRow for SHRINE-2145 Yifan is right. map...getOrElse does put all the error bits in the same spot. Got rid of Unit vs method name warning for SHRINE-2145 Switched to timeoutSeconds for SHRINE-2145 Changed Promises to be Promise[Unit] for identifying requests for SHRINE-2145 Switched to UUIDs for identifying requests for SHRINE-2145 Test of trigger to change data for SHRINE-2145 Allow trigger to change data, plus some updated comments for SHRINE-2145 Making the right Promises, and fulfilling one of them. SHRINE-2145 A little code rearranging for SHRINE-2145 Got the delayed-to-timeout path working for SHRINE-2145 Added a test to make sure a result came back eventually for SHRINE-2145 Concurrent structures for SHRINE-2145 Notes for for SHRINE-2145 Added a detatch() for SHRINE-2145 ...