Fix ValueError when the user enters a bad cache host.
Review Request #4402 — Created Aug. 7, 2013 and submitted
Fix ValueError when the user enters a bad cache host. If the user enters a cache hostname which doesn't split properly, it makes the admin site unavailable. This is because the cache stats code was just blindly trying to unpack the values without any error handling. I've updated it to cache this case, log, and continue.