Refactor redis storage to be extensible.
Refactor redis storage to be extensible.

* Remove transaction from pipeline
* store lua script for entry acquisition on class
* move redis ping/script loading to initialize_storage method.

alisaifee/limits,alisaifee/flask-limiter,alisaifee/flask-limiter,joshfriend/flask-limiter,joshfriend/flask-limiter,alisaifee/limits