Fixes #6821/BZ1117636: fix link to activation keys on CV delete page.

The link to manage individual activation keys was incorrectly using
$state.href().  This commit fixes the usage of $state.href() when
constructing the activation keys link.

http://projects.theforeman.org/issues/6821
https://bugzilla.redhat.com/show_bug.cgi?id=1117636