Slightly simplified development install

Changes: 
* Added missing steps to README.md
* Added requirements.txt. Eliminates the cycle of running app, seeing a failed import, pip installing, and repeating. 
* Removed dependency on Amazon SES for development (hopefully)

Note that this is (obviously) untested in deployment. If there is a typo or similar inside of

  if not DEVELOPMENT:

I have no way of knowing about it.