code: function updatePackageInfo(theme, version) {
    const cwd = `.tmp/${version}/${theme}/publish`
    bower.version = `${version}-${theme}`
    pkg.version = `${version}-${theme}`
    return Promise.all([
      fs.writeFile(`${cwd}/bower.json`, JSON.stringify(bower, null, 4)),
      fs.writeFile(`${cwd}/package.json`, JSON.stringify(pkg, null, 4))
    ])
  }
docs: Creates bower.json and package.json with content relevant to theme.
  @param  {String} theme   Theme name
  @param  {String} version Semver
  @return {Promise}