New python-opentsdbclient repo

OpenTSDB is a time-series database, and there is a wish to use it
as a backend for Gnocchi project. OpenTSDB has no sufficient
Python client presented, so we need to implement a simple one
as a stackforge project.

Change-Id: I17f728d77986f593d240eef3b5705651688b464e
Merge "New python-opentsdbclient repo"