Updated example app to work with Django >= 1.8

[darrellsnow]

Added the django-environ class to ease setttings logic. Modified the settings to a more modern TEMPLATES configuration. Updated the requirements.txt to include django-environ and django-vanilla-views. Updated the README.md to be accurate for Django >= 1.8. Corrected permissions on the manage.py to be executeable.

[tomchristie]

Not clear to me why the ci tests are failing. May be an unrelated aspect, that we need to remove --use-mirrors from the script. Want to add that in as a change too, and see if it resolves the test failures? Thanks for your work on this! 😄