Mailer

*Not ready to be merged yet!*

I got basic email-sending capabilities working, but I still want to add more stuff: 

- [x] UserMailer testing. 
- [x] Basic QR codes
- [ ] Confirmation emails 
- [ ] QR codes in email confirmation

**ALSO you need to add ```QWIKSTUBS_GMAIL_PASSWORD``` to your application.yml file.** I'm not gonna post the password on here, so just ask me for it if you don't already know it.