code: function deepExtend(target, source) {
    _.each(source, function(value, key) {
      if (_.has(target, key) && isObject(target[key]) && isObject(source[key])) {
        deepExtend(target[key], source[key]);
      } else {
        target[key] = source[key];
      }
    });
    return target;
  }
docs: Performs a deep merge of two objects, source into target.
  
  @param  {Object} target
  @param  {Object} source
  @return {Object}