Search all dependencies to check which books to build
Search all dependencies to check which books to build

So far we only checked one level of depth for inclusion of modified files.
This let to missed book builds.

Now, we check all dependencies, even over multiple includes.

Rename args to silence pylint warnings.

Change-Id: I78df8803f17cdb736230c2137277bb3886071e85

AlekhyaMallina-Vedams/openstack-manuals,openstack/openstack-manuals,potsmaster/openstack-manuals,gongysh2004/openstack-manual,AlekhyaMallina-Vedams/openstack-manuals,potsmaster/openstack-manuals,saeki-masaki/openstack-manuals,openstack/openstack-manuals,gongysh2004/openstack-manual,openstack/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,Akasurde/openstack-manuals,kairoaraujo/openstack-manuals,saeki-masaki/openstack-manuals,openstack/openstack-manuals,kairoaraujo/openstack-manuals,Akasurde/openstack-manuals