adding an optional "default" 2nd param to Model.get().
adding an optional "default" 2nd param to Model.get().

renaming Model.changed to Model._changed. _changed is now reset to false after the change events are triggered
for whatever change happened.

added a collection convenience function (Collection.each()) for running all a colleciton's models through the
given function.

lyonbros/composer.js,lyonbros/composer.js,lyonbros/composer.js