Use babel to generate translation file

Use babel to generate translation file

Fixes bug 1103519

Following http://wiki.openstack.org/Translations to integrate transifex
translation into quantum

We added the empty file quantum/locale/quantum.pot to avoid the
failure of the Jenkin's translation-jobs because git doesn't allow empty
directory to be added into the repository.

After this patch accepted, we need to do as below:
1. Make the transifex quantum project
(https://www.transifex.com/projects/p/quantum/) as part of the
openstack transifex project hub and give access to the transifex
openstack Jenkins account.

2. Add the translation-jobs into openstack/openstack-ci-puppet for
ceilometer.

Change-Id: I329a8bdc51ed8a0e75399c592d3991b1ec06a855