Build ckan documentation using sphinx and upload

[rgrp]

Use python sphinx to build documenation in ./doc and then upload it somewhere publicly accessible.

NB: improving the documentation is another matter (as is integrating e.g. existing api docs).

Upload location options (need to decide!):

• ​http://doc.ckan.net/
• ​http://knowledgeforge.net/ckan/doc/
• ​http://www.ckan.net/doc/