Update README.rst to include Python and testing instructions.
Update README.rst to include Python and testing instructions.

This updates the README to include missing instructions for
installing the Python module and basic information on testing.
Additionally, a link to the planning etherpad is also included.

Change-Id: I75795888bd19eb8116d86ee9647a2eeb6f3119be

openstack/stackviz,openstack/stackviz,openstack/stackviz