Version css and js files of the form based on selectable version

--HG--
branch : static_file_versioning
Merged in ustun/django-selectable/static_file_versioning (pull request #20)

Version css and js files of the form based on selectable version
Include Ustun Ozgur in the authors file.
Include testing Django 1.6 in the tox environment.
Updating grunt to test latest jQuery and jQuery UI versions.
Note in the setup.py that Python 3 is supported.
Release note about most recent change.