Hash cache break

This replaces the `?v=2.0.0.0` with `?h=xxxxx` this helps the cache stay valid for much longer than it does right now. for example `bootstrap.css` or the `require.js` files are very rarely updated but they get cache invalidated with every update. this will help us only invalidate them when they are actually changed. same with other files but with a lesser degree.  no need to invalidate `app.js` on a server side only update.