* Episode - changed getDataFormat() to static, so it can be called from
any class, just to keep things standard.
* Podcast - Created a method called addEpisode(Episode) which will add
the episode chronologically (ordered by date) newest first. Also set up
the update method to add a new episode via this function rather than
directly to the array of episodes.
* DataStorage - Changed the loadPodcast(Podcast) method, so it will use
the method in Podcast to add a new episode.