Edx-organizations

Auto releasing was not working. Make changes to fix it so we automatically release from travis to PyPI.

The major user facing change was that we unpin `djangorestframework` so that upstearm dependencies can upgrade to newer versions of DRF.

We also did a bunch of dev improvements to bring this library up to the current edx standards for python package management and testing.

[PR41](https://github.com/edx/edx-organizations/pull/41)

[PR39](https://github.com/edx/edx-organizations/pull/39)

Adds in tox and runs tests with both Django 1.8 and 1.11.