Trim Back-end authentication code

[dmullen17]

I cut down one of the two re-directs in the code authorization flow. This formerly redirected to localhost:8888. I updated it to:

            <a className='Login-button' href='http://localhost:8888/login' >Login with Spotify </a>

This way the user doesn't have to click on two buttons to sign in with spotify. I can probably remove a good chunk of the back end code that renders the first page.