Ui improvements

see https://github.com/theforeman/staypuft/wiki/UI-Parameters-for-new-wizard
cc @sseago 
**NOT READY**
Oh I see here, yeah this code would assume that the default param values would be pre-set on the deployment prior to displaying this form -- i.e. at the point where we do Deployment.new -- we should probably have some .each loop where we set a default value for all of the UI params in a hash. I don't see this set anywhere here, but that should be a relatively straightforward follow-on commit to add to this PR.