Added the underscore node_module.

node_modules/underscore/modules/partition.js

@@ -0,0 +1,7 @@
+import group from './_group.js';
+
+// Split a collection into two arrays: one whose elements all pass the given
+// truth test, and one whose elements all do not pass the truth test.
+export default group(function(result, value, pass) {
+  result[pass ? 0 : 1].push(value);
+}, true);