change to GalleryCollection of models.Photos
reorganize models.Shot to extend models.Photo, push templates into Shot.prototype

* add Shot.fetchHiddenShots(),
* connect to ThumbView  through model.trigger('fetchedHiddenshots')
* and GalleryCollection through .collection.trigger('fetchHiddenShots')
checkpoint: show hiddenshot complete,

* add GalleryCollection.fetchHiddenshots()
* add HiddenshotCollection as a property to models.Shot, use models.Shot.set('hiddenshot')
* todo: hide hiddenshot on 2nd click
clean up Class heirarchy/inheritance patterns