Adds ability to extend the Model and Collection from within the adapter

This PR make the below possible:

	module.exports.afterCollectionCreate = function(Collection) {
	    // custom interface
	    _.extend(Collection.prototype, {
			// extended functions and properties go here
			foo: function(){
				Ti.API.info("My custom adapter relevant functionality");
			}
		});
		
		return Collection;
	};