Default publicPath value, relative publicPath
Hi,
thanks for writing this loader. It integrates nicely in our Webpack configuration.
However I've noticed a small issue connected with the default value of the publicPath.

According to the Webpack [docs ](https://webpack.js.org/configuration/output/#output-publicpath) the default value for publicPath is an empty string, which means relative to the page. This is the case in my app and in the production build I omit defining the publicPath. When using this loader in the urls for the font I have absolute url (starting with /). I suppose the issue is on this [line](https://github.com/jeerbl/webfonts-loader/blob/master/index.js#L152).

Note: If the path is relative in the urls for the fonts, through the css-loader, Webpack will require the file and fail because the file does not exists. Any ideas on how we can fix this?



