feat(dart/transform): Generate DirectiveMetadata for exports

For all files that export another library, include `DirectiveMetadata`
for the exported library in that file's associated `ng_meta.json` file.

modules/angular2/src/transform/common/directive_metadata_reader.dart

@@ -40,7 +40,7 @@ class _DirectiveMetadataVisitor extends Object
       }
       meta = new DirectiveMetadata(
           type: directiveType,
-          compileChildren: false,
+          compileChildren: true,
           properties: {},
           hostListeners: {},
           hostProperties: {},

modules/angular2/src/transform/common/formatter.dart

@@ -8,7 +8,7 @@ DartFormatter _formatter = null;
 
 void init(DartFormatter formatter) {
   if (_formatter != null) {
-    logger.warning('Formatter is being overwritten.');
+    logger.info('Formatter is being overwritten.');
   }
   _formatter = formatter;
 }

modules/angular2/src/transform/common/names.dart

@@ -4,9 +4,32 @@ const SETUP_METHOD_NAME = 'initReflector';
 const REFLECTOR_VAR_NAME = 'reflector';
 const TRANSFORM_DYNAMIC_MODE = 'transform_dynamic';
 const DEPS_EXTENSION = '.ng_deps.dart';
-const META_EXTENSION = '.ng_meta.dart';
+const META_EXTENSION = '.ng_meta.json';
 const REFLECTION_CAPABILITIES_NAME = 'ReflectionCapabilities';
 const REGISTER_TYPE_METHOD_NAME = 'registerType';
 const REGISTER_GETTERS_METHOD_NAME = 'registerGetters';
 const REGISTER_SETTERS_METHOD_NAME = 'registerSetters';
 const REGISTER_METHODS_METHOD_NAME = 'registerMethods';
+
+/// Returns `uri` with its extension updated to [META_EXTENSION].
+String toMetaExtension(String uri) =>
+    _toExtension(uri, const [DEPS_EXTENSION, '.dart'], META_EXTENSION);
+
+/// Returns `uri` with its extension updated to [DEPS_EXTENSION].
+String toDepsExtension(String uri) =>
+    _toExtension(uri, const [META_EXTENSION, '.dart'], DEPS_EXTENSION);
+
+/// Returns `uri` with its extension updated to `toExtension` if its
+/// extension is currently in `fromExtension`.
+String _toExtension(
+    String uri, Iterable<String> fromExtensions, String toExtension) {
+  if (uri == null) return null;
+  if (uri.endsWith(toExtension)) return uri;
+  for (var extension in fromExtensions) {
+    if (uri.endsWith(extension)) {
+      return '${uri.substring(0, uri.length-extension.length)}'
+          '$toExtension';
+    }
+  }
+  return uri;
+}