[Reviewer Matt] Memcached redundancy

Matt

As discussed, can you review my Chef changes for memcached redundancy.  I have tested these live and verified that the server lists passed to sprout are correct and that it is being kicked to read the file.  Unfortunately the sprout nodes being quiesced seem to assert every time at the moment, grabbing a lock in PJSIP, so I can't completely run through my test case, but I'm happy the chef scripts are doing the right thing.

Mike