* Get rid of runtests.py
 * Moved test code  from rest_framework/tests and rest_framework/runtests to tests
 * Invoke py.test from setup.py
 * Invoke py.test from Travis
 * Invoke py.test from tox
 * Changed setUpClass to be just plain setUp in test_permissions.py
 * Updated contribution guideline to show how to invoke py.test