Don't use redis `keys`.
ensure that we don't bork because of a process which doesn't exist anymore
Revert "Don't use redis `keys`."

This reverts commit 4e3b6c002b0549e35566eddf8067cc685ec6c595.
Resque already contains the known list of hosts.  Use that
make sure we're not calling online hosts stale
Merge pull request #3 from seomoz/tubo-3004

Tubo 3004