Add Tuskar UI Extras

You can use RHEL 7 with RDO, not just RHOS. Yet, RDO wouldn't have tuskar-ui-extras. Unfortunately, we may need to duplicate the json file and have a separate one just for RHOS. That's kinda fugly and  isn't a clean interface right now, so some rafactoring is probably in order longer term to make that easier to do. For now though, I'd think be OK to just have a separate json file for RHEL 7 + RHOS 6 that installed tuskar-ui-extras.