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
XenAPI: Fix declare definition

Some versions of bash do not initialise a variable with declare -a
therefore with set -u bash can terminate the script.

Be more verbose in declaring the array if it is not set

Change-Id: I6ec2b6e986aeffe539a2ab93432fa7af9e5a4f5d
Merge "XenAPI: Fix declare definition"
Merge "Install gettext from apt on Trusty (Ubuntu 14.04)"
Merge branch 'master' of https://github.com/openstack-dev/devstack