purge all bitmask_client documentation

elijah wants leap_doc to be the authoritative source. so:

• remove sphinx project
• delete read the docs project
• delete pythonhosted.org documentation.

This is waiting until the conversion to .md is done.

(from redmine: created on 2013-10-22, closed on 2014-03-31, relates #3934 (closed), relates #5300 (closed), relates #5330 (closed))