Collection FormType updates

* Added additional data attributes for collections:
	* data-form-widget="collection" - defines that the field is a collection
	* data-collection - defines that the field is a collection
	* data-collection-allow-delete - defines collection items can be deleted
	* data-collection-allow-add - defines collection items can be added
* Added `prototype_name` as view variable rather than accessing prototype.vars.name
* Updated .twig and php templates