Feature/84 send email support

- Setup letter opener and wrote rspec tests for confirmation of sending to user. 
- Tested compatibility with browser outside vagrant environment. 
- DID NOT add ability to use letter opener in vagrant. Letter opener docs suggests using Mailtrap or MailCatcher. 

https://trello.com/c/wH8gCm6j


Letter opener doesn't work with vagrant right? See https://github.com/fgrehm/letter_opener_web#usage