[wai-app-static] Provide sample.hs for actual wai-app-static

Hello All,

I tried to use example from `wai-app-static` but got some problems with it. Actually there are no `fileSystemLookup` in `Network.Wai.Application.Static`, `ssMaxAge` now is in `WaiAppStatic.Types` and etc...

Here is working version of example with the current wai from master.