Redis as dependency (predis && snc/RedisBundle), in order to collects statistics

This PR is intended to give a sort of statistics #32.

simple solution, when a controller is called, a listener stores on redis some statistics:

https://github.com/liuggio/badge-poser/blob/9eadf0617c212e2a58a5a27ffb3fdbac92caee05/src/PUGX/BadgeBundle/Service/Statistic/PersisterInterface.php