Added the underscore node_module.

node_modules/underscore/cjs/_set.js

@@ -0,0 +1,21 @@
+var isNumber = require('./isNumber.js');
+var isArray = require('./isArray.js');
+var isObject = require('./isObject.js');
+
+function set (obj, path, value) {
+  var key = String(path[0]);
+
+  if (path.length === 1) {
+    obj[key] = value;
+    return;
+  }
+
+  if (!isArray(obj[key]) || !isObject(obj[key])) {
+    var nextKey = path[1];
+    obj[key] = isNumber(nextKey) ? [] : {};
+  }
+
+  return set(obj[key], path.slice(1), value);
+}
+
+module.exports = set;