Adds Babel-1.3.tar.gz

The Zuul client uses babel.dates.format_timedelta which was introduced
with 1.0 http://babel.pocoo.org/docs/changelog/#version-1-0
Ubuntu Precise has 0.9.6 causing the Zuul client to abort because of the
missing method.

https://review.openstack.org/112574

Change-Id: I3d00bb5f1737d5286fd6fbb2aa83f0a21ca495f6
Merge branch 'dependencies' into master

Adjust requirements.txt to point to the tarballs of:
- PrettyTable
- six
- Babel

Change-Id: I7c76c76f5b2e213b7ea71a3ab019cb7a895b50a8