Add metrics reporting module to worker-svc and implement a default Graphite reporter

Consider how to plug in metrics reporting capabilities. Graphite and Ganglia are supported with the metrics-graphite and metrics-ganglia modules, respectively. I think it may be a per worker configuration not a per job configuration. I was also uncertain if you'd prefer a hierarchy of Maven modules for metrics reporting or if it is sufficient to plug this into the worker modules. Certainly the latter required less effort.

I'm a Guice noob so may not have the bindings correctly done.