Added some null ref protection in the case where certain properties of an object were not set, fixed length documentation to read seconds instead of milliseconds
Added global maps of artist, album, and track information keyed on musik id that are populated automatically by API calls. These will be used to fetch rich information about an object that we don't want to store in the html attributes
Modified client to extract track mime type from global tracks dict instead of html template. Hooray for separation of model and view!