Support static files with LiveServerTestCase.

Change the Django 1.7 dependencies in the tox.ini so they pull from pypi rather than the builds on www.djangoproject.com.

Currently the selenium related tests will fail with Django 1.7 due to LiveServerTestCase no longer serving up the static files. I have changed it so it will try to import the StaticLiveServerTestCase class first and then the LiveServerTestCase if it fails.