Merge pull request #650 from kaysoky/Warnings

Removal of unused imports and unnecessary @SuppressWarnings
- Removed existing worker in RepositoryManagers that finds and sends unsent messages
- Added two methods to ChangeDAO
Added UnsentMessageQueuer
Tests for UnsentMessageQueuer
The popper worker
Finishing the bean wiring
+ Integration test
Fix the test for changes to MessageReceiver
+ Missed compilation error
+ CloudWatch metric for Popper worker