Ensure redis is on slaves (and running)

Quite a few projects are/would like to use redis and
being able to have their tests use the slave provided
servers would be a great addition to ensure functionality
is working as expected (when mocking just doesn't cut
it).

Change-Id: I6081b6cfe1c6393c7c6f2d028c313da759220a72
Merge "Ensure redis is on slaves (and running)"