Ui improvements

see https://github.com/theforeman/staypuft/wiki/UI-Parameters-for-new-wizard
cc @sseago 
**NOT READY**
This is a change from current seeds.rb behavior, where we ignore puppetclasses that aren't found. The reason for this is there's a bit of an ordering dependency problem -- foreman installer initially runs db:seed prior to loading puppetclasses, and then the staypuft installer runs it again after importing classes. I suspect this exception raise here will break the installer, so we should ignore not-found classes here just like we do elsewhere.