webpack  pulicPath不支持相对路径

如下代码

https://github.com/easy-team/easywebpack/blob/master/utils/utils.js#L58


```
utils.normalizePublicPath = publicPath => {
  publicPath = `${publicPath.replace(/\/$/, '')}/`;
  if (!utils.isHttpOrHttps(publicPath) && !/^\//.test(publicPath)) {
    publicPath = `/${publicPath}`;
  }
  return publicPath;
};

```
上述代码中publicPath被强制设置成绝对路径，是否可以支持设置相对路径 



