Adjust language of LMS emails to work specifically for Stanford. Here
there be dragons: lots of ugly conditionals that will need to be
changed once we develop a way to "theme" arbitrary strings throughout
the site.

Instead of hardcoding things like the platform name, use the
corresponding overrideable settings instead. This allows themes to
control emails as well.

 - issue is that content machine isn't whitelisted for email
 - this also provides secondary filtering for user registration

  - django debug commented out in lms/envs/dev.py (temporarily - need cleanup)
  - email backend set
  - index page modified for edx4edx