We now have a base test case class for Predis (namely PredisTestCase)
grouping various commonly used utility methods shared by all of the
tests in the suite, greatly improving reusability.
Starting with 2.6, Redis uses a slightly different format for the payload
returned by MONITOR for each command. Predis can now adapt to this difference
and returns a new `client` field in the payload object. This new field is
always defined but is set to NULL when connected to Redis < 2.6.
Please note that Redis 2.6 now does not echo the `MONITOR` command as the
first payload when opening a new MONITOR context.
Daniele Alessandri