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


All emails are notifications. With this type of class you're basically saying that this mailer is the only mailer as it's responsible for every notification. Rename to be more specific.