Added fetch tracks to a separate file
Added and improved the player in its own scope.
Added player input for passing in username (testing)
Commented out, original fetchTracks and integrated fetchUsername function

Commented out, original fetchTracks and integrated fetchUsername
function to pass through input data.
Added default state "karan" and to automatically play after songs fetched.
fetchUsername update

Changed naming convention for fetchUsername to login, also added
ability to pause the player when changing username.
Changed default username instead of 'karan', added error response