Add support for svg fragment

Should fix #459 

Also add support for usage of SVG sprites use SVG4Everybody which means you can do:
```html
<svg className="edit">
  <use xlink:href="mysvgsprigte.svg#edit">
</svg>
```

For more information see [jonathantneal/svg4everybody](https://github.com/jonathantneal/svg4everybody)