Rather than figure out how to upgrade the Stripe gem to be compatible with future Rails, I'd rather just delete the references, since it's currently unused.
I'm not so bold as to go in and fully trash all our donation code; I just want to ensure we're not sending people down broken codepaths, and that if they reach them, the error messages are clear enough.
This commit will require a few changes to the deployment process:
* store AWS credentials in AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY env vars
* store OpenNeo Auth credentials in OPENNEO_AUTH_APP, OPENNEO_AUTH_SERVER, and OPENNEO_AUTH_SECRET env vars
STRIPE_SECRET_KEY and STRIPE_PUBLISHABLE_KEY are now required, too; better have a good .env.
You can always put in dummy values if you have no credentials, though; they only get called up if there's a transaction.
SECRET_TOKEN is now an env var, too, but the production deploy process currently replaces config/initializers/secret_token.rb anyway; this might be the way to go later, though.
