Fixes #7120/BZ980113: use BS3 on dashboard to make it responsive.

The dashboard was displaying badly in smaller browsers.  This
commit reworks the dashboard to use bootstrap 3 classes and
thus makes it responsive.

http://projects.theforeman.org/issues/7120
https://bugzilla.redhat.com/show_bug.cgi?id=980113
Merge pull request #4601 from waldenraines/7120

Fixes #7120/BZ980113: use BS3 on dashboard to make it responsive.