Add Sphinx and apidoc directory tree and setup for readthedocs. Convert README and HOWTO to rst to populate initial userguide pages. http://distaf.readthedocs.io/projects/distaflibs-gluster/
REVIEW: http://review.gluster.org/14794 (distaflibs-gluster: Add sphinx docs and necessary RTD updates) posted (#1) for review on master by Jonathan Holloway (jholloway)