add support for django > 1.6.X
stop using pip mirrors
do not run south tests on django > 1.6.X
Merge pull request #161 from brad/django_1.7

Django 1.7
Update the travis matrix to get closer to passing tests.
Django==1.7 REUSE_DB=1 #174; Django==1.5 Python3 skip --with-profile
Merge pull request #177 from conrado/master

Django==1.7 REUSE_DB=1 #174; Django==1.5 Python3 skip --with-profile
Simplify travis config, remove master for now.