For the RST guides, we do not need doc/source, since doc is always
empty. Use source directly.
This syncs the setup used here with openstack-manuals.
Rename top-level from openstack-firstapp to firstapp, there's no need
for the long name in this repo.
Change-Id: If4e11a4f90d580876865348e0d88b92cec4b6659
f58477ef61