Install gettext from apt on Trusty (Ubuntu 14.04)

The binary 'msgfmt' is not installed as part of python-gettext for Trusty
(Ubuntu 14.04), so gettext needs to be installed from apt.

Change-Id: I415814559d82be453e978a0d92a0cdb38f105683
Closes-Bug: 1331328
Merge "XenAPI: Fix declare definition"
Merge "Install gettext from apt on Trusty (Ubuntu 14.04)"
Merge commit 'refs/changes/83/86083/2' of git://gold.eng.hq.xensource.com/git/github/openstack-dev/devstack into tmpbranch