First implementation of automatic recognition of redirect url

[jfaltis]

This is my first approach of implementing #96. The local webserver now starts just before the token request and listens for incoming GET requests. When a get request is received it tries to "parse" the URL. If the start of the webserver fails or the GET request cant be parsed it returns to manual authentication (old way).

The problem I see with the current state of my implementation:

• If the redirect url is not aimed at port 8888 but at a different port (since this can be configured in the Spotify Dashboard) the program would wait for ever because it won't receive a GET request. I guess I have to implement some kind of timeout after which the program will return to manual authentication.

What do you think?

[Rigellute]

Great work @jfaltis!

Not sure how concerned we should be if the redirect URI was entered incorrectly to Spotify, however, I like your suggestion of adding a timeout.

This could probably be implemented later though.

I'm going to merge this into another branch so I can test before we merge to master.

Really great work!