Make it possible to transform asset URLs with vue-visual

[Robert Reinhard]

See https://vue-loader.vuejs.org/guide/asset-url.html#transform-rules and transformAssetUrls

{
  video: ['src', 'poster'],
  source: 'src',
  img: 'src',
  image: ['xlink:href', 'href'],
  use: ['xlink:href', 'href']
}

I bet I could add vue-visual to this list...

[Robert Reinhard]

Eh, I think I misunderstood that option, I don't think this is just for creating require statements for asset tags.