cleanup requirements and settings

major changes follow. cleaning up requirement files and making some changes to settings files. main goal is to pare down dependencies and streamline settings files (which are currently misnamed/confusing)

there are four instances in which we run the project:
- travis (CI and testing)
- local development
- staging (heroku and/or deis)
- production (deis and/or heroku)

the proposed changes is that each uses the following sets of requirements and settings:
- travis: `travis.py` and `dev.txt`
- local dev: `dev.py` (formerly `local.py`) and `dev.txt`
- staging: `staging.py` and `prod.txt`
- production: `prod.py` and `prod.txt`

so a lot of settings are slowly being pruned/moved around, and a _lot_ of dependencies have been moved and deleted. please check to see if anything you _know_ you use in your module has been deleted and add a comment to let me know to restore it. I purposely deleted more than necessary so we can slowly rebuild reqs one by one.

maybe add `django.contrib.messages.context_processors.messages` here for using the Django Messages Framework