Fixes #6174/BZ 1020808 - ensure host advanced info link is displayed.

The problem was that the event 'contentHost.loaded' only fired upon
the first visit to this page.  Using the $promise instead results
in the advanced info link being displayed each time.

http://projects.theforeman.org/issues/6174
https://bugzilla.redhat.com/show_bug.cgi?id=1020808