that part is done by `modown-static`, where `express-yui` will just set up a middleware per group pointing to the proper build folder for each group, the rest is done by the other pkg. A side note on this: `modown-static` is probably equivalent to `combohandler`, it just uses stream and express.static under the hood, plus some custom combo setting to avoid the use of `&` and `?`. In the feature, we should look into consolide those two pkgs.