(Fixes #3064) Links to hostgroups are consistent

In the host list view, the hostgroup link points to the edit view. However, in the host detail, it points to "search=hostgroup+%3D+aisusie%2Fdevel%2Fbackend" which is wrong too.
It'd be nice if both pointed to search=hostgroup_fullname=HOSTGROUP.

credits to https://its.cern.ch/jira/browse/AI-2624

When the user is in the hosts list view, it's confusing that when you click on a hostgroup it does not simply search for all hosts in that hostgroup, but instead it leads you to the edit page.

http://projects.theforeman.org/issues/3064