python-django: new package

[Thomas:
 - Bump to Django 1.7.2, the latest available version;
 - Support Python 3 in addition to Python 2.
 - Use a download location from pypi.python.org since the download
   location from djangoproject.com didn't work as is and is
   impractical to use with Buildroot: the full URL of the tarball is
   https://www.djangoproject.com/download/1.7.2/tarball/

. I.e, it does
   not end with the tarball file name.]

Signed-off-by: oli vogt <oli.vogt.pub01@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>