Add hash to production bundles file name

[EcutDavid]

https://webpack.github.io/docs/long-term-caching.html#option-1-one-hash-for-the-bundle

Add this feature can prevent caches from user's browser block our latest bug fix.

[weblogixx]

Hi @EcutDavid,

that would be a nice addition. Will think about it and eventually include it in the default. Thank you!