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

* Add more granular tests in the client features test suite.

* 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