Removes Model.setup() left over from Backbone Relational.
Adds code for prefetching file resources, then instantiating them as objects with a cached fetch.
Adds ProgressBarView to show loading progress.
Adds message div to Experiment View to allow showing of messages to users.
Preloads experiment assets and shows progress bar at beginning of experiment.
Adds jquery-ajax-progress to track progress of ajax requests.
Adds TrialObject Views, and optional subView selection based on model polymorphism.