Test handlers update cache latency stats
Finish remaianing handler stats tests
Check a 3004 diameter response causes handlers to record a penalty
Remove stats testing so they can be refactored into new tests
Add stats tests fixture
Re-add stats tests
Remove test code that is not required for stats tests
Better commenting for cache stats tests
Better commenting for successful MAR
Better commenting for remaining tests
Merge remote-tracking branch 'origin/master' into stats_handler_uts
Fix up handler stats UT memory leaks
Take latest cpp-common
Merge pull request #41 from Metaswitch/stats_handler_uts

[No review required] Handler stats UTs.