Fixes #7283: using translate filter in <th> to avoid infinite loop.

Changing this table header to match the rest of the ones in bastion
and thus avoiding an infinite loop created by the interaction between
the translate and sortable directives.

http://projects.theforeman.org/issues/7283
Look at the long description in the commit, it only happens when both `sortable` and `translate` are used.  I could change this one over for consistency if you like (and I actually started to) but directives are more performant than filters so I left it.