Inital RiakCS docs for OpenStack API support

Reorganize RiakCS storage API docs and add a page to show the
supported features of the OpenStack API.
Add placeholders for OpenStack API description pages
Update OpenStack API operations pages to replace placeholders with actual content
Cleanup cs links, nav, and a few sneaky changes
Remove extra character
Add more info about API options and pages showing the API mappings
Add details about Riak CS authentication options

Add documentation about the authentication options that can be used
with Riak CS. Also add documentation covering how to use Keystone for
authentication with Riak CS.
merging header ad
Merge branch 'master' of github.com:basho/basho_docs