Update contrib docstrings to match guidelines

Per http://docs.openstack.org/developer/hacking/
and http://www.python.org/dev/peps/pep-0257/

Without extra blank line in multi-line docstrings
based on http://lists.openstack.org/pipermail/openstack-dev/2014-February/028156.html

Blueprint: reduce-flake8-ignored-rules

Change-Id: I0050d382369d3013280f3d90df87fb530bc6c939
Merge "Update contrib docstrings to match guidelines"