Added the underscore node_module.

node_modules/underscore/amd/once.js

@@ -0,0 +1,9 @@
+define(['./partial', './before'], function (partial, before) {
+
+	// Returns a function that will be executed at most one time, no matter how
+	// often you call it. Useful for lazy initialization.
+	var once = partial(before, 2);
+
+	return once;
+
+});