Show a warning if not all essential provisioning templates are associated with an OS
When configuring an OS Foreman shows a warning if no template is associated with it. But as soon as at least one template (but not all needed) templates are associated the UI won't show a warning. The user could then potentially create a broken config without even knowing it.
See the attached screenshot showing an example. For Debian Jessie, only a PXELinux template is associated so that's the only template category shown in the interface.