Adds collection specific javascript to handle dynamically creating/removing elements on the new collection form page.  Defines custom setters for personal/corporate creator names in the Mods datastream that ensure proper node placement and disallow blank or empty entries.  Updated views to reflect more complete model/behavior.  Updated config/application.rb to load the lib/helpers directory.  Factories.rb now shows how to build a Datastream object that can't be saved, nu_mods_datastream_spec.rb added and fleshed out in favor of the too-specifically named nu_mods_collection_datastream_spec.rb.  Added a module, node_helper.rb, that lets us manipulate root elements in a Datastream document in a reasonably intelligent fashion.