Option "indent" has no effect in version 0.6.2

Setting more than the default 2 spaces as an option for indents does nothing:

`const builder = new xml2js.Builder({
        pretty: true,
        indent: '    ',
        newline: '\n'
      });`

Only if you change the spaces in the file **lib/defaults.js** it works:

`renderOpts: {
        'pretty': true,
        'indent': '    ',
        'newline': '\n'
      },`