We just lost the docs.o.o index page: The tox run failed and only a
few files were ready. Since we delete existing content when pushing new,
this removed all our static pages.
Add a safe guard for all doc building: Only collect and publish
documents when we have build them with success. Add this to related
roles like creating/destroying afs as well.
Change-Id: Ife2496fe920bd40d52803705b409e6e621532254