allow different pathPrefix per result target

[chmontgomery]

e.g. bundle.result should accept an object like this:

{
  dest: './',
  pathPrefix: [
    {
      env: 'default',
      val: '/public'
    },
    {
      env: 'staging',
      val: 'http://mw3.stg.wsj.net/public'
    },
    {
      env: ['production', 'prodore', 'prodvir'],
      val: 'http://mw2.wsj.net/public'
    }
  ]
}

[timelf123]

I like the env definitions. I suppose the same thing can be accomplished now by checking env before the plugin runs (and setting pathPrefix), then passing to https://github.com/dowjones/gulp-bundle-assets/blob/master/docs/API.md#optionspathprefix