Ui improvements

see https://github.com/theforeman/staypuft/wiki/UI-Parameters-for-new-wizard
cc @sseago 
**NOT READY**
Hmm. I guess we could try this. Initially I had this as a before_save, but then needed to move it a little earlier to deal with validation problems. The only downside to that is this creates a hostgroup -- that would mean that Deployment.new would create something in the database, while ordinarily .new will not do that. Actually either way we have an edge case where if validation fails, the hostgroup is already created, and then later when we try to create it again, the step fails.