Fixes #5745/BZ963572: upgrade angular-gettext to fix XSS.

The library Bastion uses for i18n, angular-gettext, was
vulnerable to XSS.  This commit upgrades the version of
angular-gettext to one that is no longer vulnerable.

http://projects.theforeman.org/issues/5745
https://bugzilla.redhat.com/show_bug.cgi?id=963572