Signalbox

- Push button install on Heroku
- Defaults to using mailgun (for simpler Heroku installs)
- Defaults to serving static files with dj-static
- AWS used only for user-submitted uploads (answer and study models)
- Cleaning up settings and env var handling

- More 1.7 fixes
- Improved display of replies and observations
- removed statlib dependency, bundling old version of the stats package

- Django 1.7 compatibility
- Improved data export using pandas/xlwt
- Small code fixes
- Conditional loading of reversion based on user settings
- Additional help text on duplicate reply resolution templates
- Changed default ordering of answers to enable better sorting in resolving duplicate replies
- Improved study change page and summary/dashboard view