Allow to work with experimental code splitting

[jnields]

Would be wonderful if this could work with code splitting.

Maybe something like this:

{
    input: [
      'src/page-a',
      'src/page-b',
    ],
    output: {
      dir: 'dist',
      format: 'system',
    },
    plugins: [
      hash({
        dest: '[name].[hash].js'
      }),
    ],
}

[jnields]

To make this work right now, this plugin would have to change the systemjs dependencies of the entry chunks.

Rather than depending on, e.g. ./chunk-a123456.js, an entry chunk should depend on a hashed file (e.g. ./bc9ad9a0f06e754084463e43971368b1b23979ce.js)