Add locals object in pug render function

[Jerffersonferreira]

This PR is going to solve this issue: #181
Now it's possible to define variables in vueify config to be used inside a pug template:

// vue.config.js
module.exports = {
  pug: {
    basedir: __dirname,
    data: {
      imageBasePath: 'https://example.com/'
    }
  }
};