[Review Queue] redis re-redux

[Cory Johns]

Greetings all.

My review queue time this week was a bit limited, due to being sick
and other conflicts on my time, but I was able to revisit Francesco's
new Redis charm (https://bugs.launchpad.net/charms/+bug/1459345) and,
with a bit more back-and-forth related to ensuring that the automated
test runner will be able to verify it without issue, I think it's
ready for the store and gave it my +1.