Fixing compiler warnings

https://www.pivotaltracker.com/story/show/81290082
I think we keep it. @cbeer and I discussed the possibility of dropping metrics several months ago with the conclusion that it would stay.
However, if we do not see uptake in the 4.0 production release, we can re-evaluate that decision.
As a note, we have a Packer.io build of Graphite that makes this capability more accessible:
https://github.com/ksclarke/packer-graphite