Don't include Cache-Control header for served assets.

lib/src/barback/barback_server.dart

Index: lib/src/barback/barback_server.dart
diff --git a/lib/src/barback/barback_server.dart b/lib/src/barback/barback_server.dart
index a159b642d72a484ed10e74e18412dbab1cd4a835..3cc9f98f2b02a383593a1db79ced4a57e7c15509 100644
--- a/lib/src/barback/barback_server.dart
+++ b/lib/src/barback/barback_server.dart
@@ -172,8 +172,7 @@ class BarbackServer extends BaseServer<BarbackServerResult> {
       var previousSha = request.headers["if-none-match"];
 
       var headers = {
-        // Enabled browser caching of the asset.
-        "Cache-Control": "max-age=3600",
+        // Enable browser caching of the asset.
         "ETag": assetSha
       };