[For review]  Fixes issues that might arise when inmemory cache is synced with the ba...

...cking store cache

[not ready for merge]
1) Need to refactor the Memcached backing store to retrieve the tuple using one method (there's repeated code in there, I need to remove the repeated code)
2) The get_birthday function is not implemented for RedisCache. I need to do this
3) Need to test the application again.