FrontEnd: User Sign Up

[AlejandroLopez1992]

As a visitor, when I visit "/", I want to click on the Sign Up button so that I register an account with my Spotify account.
Subtasks:
use user_data from authentication to send get request to back end.
if user is found, create session with user
if not found, send POST request to backend to create user,
with get or post request results create user PORO that can be passed in through Facade to dashboard.

User should be redirected to "/dashboard" after successful registration.