Feature/redistore

A new backend Redis-based, **redistore**, required to send SMSes through SMPP.
An upcoming SMPP ESME service Twisted-based, **smpp-esme-service**, will consume the outgoing queues created by the 'redistore' backend and route them to an SMSC.

To do:
 * Handle Incoming SMSes from the SMSC. 
 * App Documentation.