Report stats metrics to carbon daemon

We no longer rely on ``slipstream-metering`` but on a single Python script with no dependency and embedded tests. The script is installed along with the server RPM in the ad-hoc ``bin`` subdirectory.
By default, the script is sending data to the carbon daemon on ``localhost`` and port **2003**.

**Warning** Do not merge, for now!

This is for code review process. Merge can only happen when graphite integration is done on the UI side.