Allow for aliasing the different timer metrics

These can be set as needed in the config file and use the existing settings as the defaults.

Up until this point we've been using a fork of statsd @paperlesspost that was forked VERY early on and went in a different direction for a while. We want to get back up to trunk, but without being able to alias these new timer metrics, we loose consistency between our current metrics and would have to either migrate a lot of files, or just start from scratch. This gives us (and probably other people) the best of both worlds, being able to use statsd but having our uppers called max's and etc.