Sign up

Allow a user to sign up.

This is to implement sign up across both the frontend and backend(s).

Takes 3 fields:
- Email
- Username
- Password

Components to be implemented are:
- [ ] Front end ember code
- [ ] Clojure
- [ ] Hook up validations from the backend
- [ ] Go
- [ ] Elixir
- [ ] Node.js
- [ ] Ruby