Things to do for the ga4gh-client (and related) repos, roughly
in order of how I think they should be done:

- get a barely working client
    - change ga4gh folder to ga4gh_client
- create ga4gh_client pypi package
- docs
    - enable readthedocs
    - migrate client-related docs from ga4gh into ga4gh_client
- tests
    - ensure client code can interact with server
- create ga4gh-common package, make ga4gh and ga4gh-client depend on it
- create ga4gh-server package and migrate ga4gh to it
- make ga4gh-server depend on ga4gh-client
- cleanup
    - eliminate client code parts of server
