Make clusto versioning optional. Once disabled, new versions are simply
not created. This allows existing databases with historical versions to
work compatibly.
Bump version, fix debian docs, add license to setup.py
Switch to dh_python2
Set series to precise so that we can push to a PPA
Merge pull request #28 from synack/optional_versions

Make clusto versioning optional
Tagging new release 0.6.0