Fixes #12461 - Compute profile is properly selected.

Fixes #11643 - [API] Add preview template to host

Fixes #11307 - Add host count to hostgroups

Fixes #12478 - don't update :attached_to if parsed :attached_to is nil

Fixes #12441 - validate uniqueness for nic identifier and host

fixes #11943 - only send built mail when host is installed

fixes #11771 - ensure created HostStatuses are saved correctly

The HostStatus reported_at timestamp is now validated to match the DB
schema and populated if it's missing. HostStatus subclasses should
validate correctly without needing to call #refresh.
...

Fixes #12201 - Made parent associations finder less dependent on association name

Fixes #12328 - host STI loads subclasses

fixes #4151 - enable reports STI

Permits subclassing of ReportImporter and Report to import and store
new types of reports associated to hosts.