Use new render_instance_selector helper
Do not expose service user and passwords in UI

End users don't need to change this (and we already generate a random
password); it can still be changed in the json if really needed.
Change verbose default to false
Merge pull request #161 from vuntz/render_instance_selector

https://github.com/crowbar/barclamp-nova/pull/161

Merged by devtool for cloudsleuth