* The internals of Predis\MultiExecContext should be refactored since the code
  has become a bit too convoluted.

* Switch to smaller test units and add more granular tests that try to cover 
  every single class.

* Documentation! The README is obviously not enought to show how to use Predis
  as it does not cover all of its features.

* Missing tests for commands:
    PUBLISH, SUBSCRIBE, UNSUBSCRIBE, PSUBSCRIBE, PUNSUBSCRIBE