working metrics plugin

with makeService tests, yet to write test for options
adding twisted plugin for metrics

Forgot to add it earlier
Options tests added
working MetricsService - per unit tests

- s/main/collect_metrics with some docs
- collect_metrics take optional auth and client so that it can be called
  again
- MetricsService that calls collect_metrics with client and auth already setup
Merge branch 'master' into metrics-plugin

Conflicts:
	otter/test/test_metrics.py
s/port_options/config_options - thanks @cyli

Since there is no port option here
added TODO
added some logs
Merge pull request #713 from rackerlabs/metrics-plugin

Metrics plugin