wai-middleware-etag

WAI middleware that attaches ETags to responses for static files if they exist. Caveats: If caching is turned on, the middleware caches calculated checksums aggressively in a synchronized hashmap; checksums are calculated only once, so changes on the file-system are not reflected until the server is restarted. This middleware only calculates ETag checksums for file smaller than 1MB, otherwise it attaches a last-modified tag to the response.