Add track, add playlist, and adding playlist to rootlist

[sashman-jaspin]

Appreciate the help Nathan.

[niftylettuce]

@sashman-jaspin @adammw @TooTallNate can we get this merged?

[niftylettuce]

@sashman-jaspin @adammw @TooTallNate finishing up a merge now with master, will be submitting PR and then referencing this issue

[kimmobrunfeldt]

I merged masters from @niftylettuce and @JChapman202 to fix the login and add these playlist manipulation functions. The login and other functions work, but addTrack and createPlaylist don't work.

[kimmobrunfeldt]

I'm trying with this code:
var Spotify = require('spotify-web');

// Spotify credentials...
var username = 'kimmo';
var password = 'pass';

Spotify.login(username, password, function (err, spotify) {
  if (err) throw err;

  spotify.addTrack(
    'spotify:user:kimmo:playlist:3UknrVAWRJ2x4kzAN3z8XL',
    'spotify:track:352zfYbDFG8sxkmOAhVeuj',
    function(err, track) {
        if (err) {
            console.log('Error:', err);
            return;
        }

        console.log('added', track);
        return spotify.disconnect();
    });
});