Restore mockup-registry.
Restore mockup-registry.

The docs still need it and due to some git submodule/Makefile magic it's
too much effort to fix right now.

plone/mockup,domruf/mockup,derFreitag/mockup,termitnjak/mockup,plone/mockup,domruf/mockup,termitnjak/mockup,domruf/mockup,termitnjak/mockup,derFreitag/mockup,plone/mockup,termitnjak/mockup,derFreitag/mockup,derFreitag/mockup,domruf/mockup