added pip-accel in hope to speed up test suite on travis ci
set pip-accel env variables as global
added gevent and zerorpc to requirements
only install gevent and zerorpc on python2
turns out python 2.6 doesn't have named tuples...
python2 install line should exit correctly on python 3
added unittest2 to python2 requirements
bump py.test and pytest-django in the hope to fix tests on django master
added PIP_ACCEL_S3_READONLY as a secure variable