XD-30 - Create a simple counter service
Add tests for exception cases in repositories.  Restructure inheritance of repository tests.  Enable redis tests again to see if CI test passes.
XD-30 - Create a simple counter service
Disable redis tests for CI build
XD-28 - Create simple gauge service.
Initial basic implementation, refactorings needed to remove duplication with simple counter service, noted as TODOs in code.