[FEATURE] Distributed Cache strategy

[imyousuf]

Is your feature request related to a problem? Please describe.
There is a lot of primary key based DB reads in the flow of Message dispatch; similar calls are there for endpoints as well. We
want to avoid repetitive calls to DB for Producer, Channel and Consumer. This should reduce the load of read from DB.

Describe the solution you'd like
We are able to use golang/groupcache along with mailgun/gubernator (it will be used for #53 and has peer auto-discovery implemented).

Describe alternatives you've considered
memcached and redis were obvious alternates; but in process and in-memory will definitely result in in best performance.

Additional context
This is purely a optimization to reduce DB load.