add height option

[samehdoush]

So that we can control the height of the bar without using css

InertiaProgress.init({
  // The delay after which the progress bar will
  // appear during navigation, in milliseconds.
  delay: 250,

  // The color of the progress bar.
  color: '#29d',

  // Whether to include the default NProgress styles.
  includeCSS: true,

  // Whether the NProgress spinner will be shown.
  showSpinner: false,

  // The height of the progress bar.
  height : '2px',
})