Added README
README: Add Contributing section
Settings: Update Pivotal Tracker API to v5
Tracker: Accept token through argument
TrackerAuth: Removed TrackAuth and related classes
FromJson: New method for Story()

v5 of Pivotal Tracker's API utilizes JSON instead of XML.
GetDataFromIndex: New method to return data from index
AddLabelsFromArray: New method to join labels
Tracker: Update comment providing instructions for debugging