Add support for a "fine" barback log level.

pkg/barback/test/logger_test.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library barback.test.logger_test;
 
 import 'package:barback/barback.dart';
 import 'package:scheduled_test/scheduled_test.dart';
 
 import 'utils.dart';
 import 'transformer/log.dart';
 
 main() {
   initConfig();
 
   test("logs messages from a transformer", () {
     var transformer = new LogTransformer([
       "error: This is an error.",
       "warning: This is a warning.",
-      "info: This is info."
+      "info: This is info.",
+      "fine: This is fine."
     ]);
     initGraph(["app|foo.txt"], {
       "app": [[transformer]]
     });
 
     updateSources(["app|foo.txt"]);
     buildShouldLog(LogLevel.ERROR, equals("This is an error."));
     buildShouldLog(LogLevel.WARNING, equals("This is a warning."));
     buildShouldLog(LogLevel.INFO, equals("This is info."));
+    buildShouldLog(LogLevel.FINE, equals("This is fine."));
   });
 
   test("logs messages from a transformer group", () {
     var transformer = new LogTransformer([
       "error: This is an error.",
       "warning: This is a warning.",
-      "info: This is info."
+      "info: This is info.",
+      "fine: This is fine."
     ]);
 
     initGraph(["app|foo.txt"], {"app": [
       [new TransformerGroup([[transformer]])]
     ]});
 
     updateSources(["app|foo.txt"]);
     buildShouldLog(LogLevel.ERROR, equals("This is an error."));
     buildShouldLog(LogLevel.WARNING, equals("This is a warning."));
     buildShouldLog(LogLevel.INFO, equals("This is info."));
+    buildShouldLog(LogLevel.FINE, equals("This is fine."));
   });
 }