npm registry version 3.4.1 not match github master version

[youknowme09]

Since I set the option.index = true , but not working.
I found from npm registry loopback-ds-timestamp-mixin is different from github master version.

The main diff is es6/time-stamp.js

// github version
const options = Object.assign({
    createdAt: 'createdAt',
    updatedAt: 'updatedAt',
    required: true,
    validateUpsert: false, // default to turning validation off
    silenceWarnings: false,
    index: false,
  }, bootOptions);

// npm version
  const options = Object.assign({
    createdAt: 'createdAt',
    updatedAt: 'updatedAt',
    required: true,
    validateUpsert: false, // default to turning validation off
    silenceWarnings: false,
  }, bootOptions);