* Add ability to inject statsd client; some py test/reqs updates
- Updated the metrics logger to allow construction with an existing
statsd client, so that it can be configured by external systems or libs.
- added requirements to requirements-dev.txt which are needed to run
tests-eg coverage, nose
- removed dependency on mock lib, it is in python stdlib now
- updated tox.ini to remove the now-superfluous deps
* add license to test file, and remove blank line at EOF