Added runit support for running multiple carbon-cache daemons

This allows runit to manage multiple carbon-cache daemons. I have included tests with this pull request to make it easier to verify. 

It looks like some of the integration tests on master don't actually work. I could not get the CentOS-64 and Ubuntu 10.04 tests to work at all. I tested against the default-ubuntu-1204 and the carbon-cache-ubuntu-1204 tests. I did not clean up the other tests here because I did not want to muddy this pull request. 

I would love some feedback and a code review if someone has time.