Enable cache busting for assets on deploy

[fcaps]

What happened:
a route got removed from production "js/app/members/newshub.json"
this route was called from a js file that got cached in the reverse-proxy.

to overcome this issue, assets should be loaded with a version qyery-parameter like "https://faforever.com/js/app/newshub.js?v=2"

[fcaps]

after investigating a bit, it seams like grunt is not supported when it comes to cache busting.
there is a plugin but there is no pug plugin for it.
writing such a plugin would be a waste of time, since webpack is better maintained and there is even a pug plugin for cache busting , swithing to webpack is a good idea in general.

[JaviTrek]

@fcaps switching to webpack would be peak, grunt is just terrible all around.

Do you need help with that? It shouldn't be too hard

[fcaps]

@JaviTrek you could review the PR :)

open tasks if you like to do them:

• move scss to webpack
• move to webpack devserver (https://webpack.js.org/guides/production/)
• remove whats left from grunt
• update Dockerfile/-dev