Validate that an uploaded package has a LICENSE file.

utils/pub/validator.dart

Index: utils/pub/validator.dart
diff --git a/utils/pub/validator.dart b/utils/pub/validator.dart
index 584a21416f3d054554c614d593bf77184e529703..4de60ce3b4a179b344d1e26f02eef741afa4bfe0 100644
--- a/utils/pub/validator.dart
+++ b/utils/pub/validator.dart
@@ -8,6 +8,7 @@ import 'entrypoint.dart';
 import 'io.dart';
 import 'system_cache.dart';
 import 'utils.dart';
+import 'validator/license.dart';
 import 'validator/name.dart';
 import 'validator/pubspec_field.dart';
 
@@ -38,6 +39,7 @@ abstract class Validator {
   static Future<Pair<List<String>, List<String>>> runAll(
       Entrypoint entrypoint) {
     var validators = [
+      new LicenseValidator(entrypoint),
       new NameValidator(entrypoint),
       new PubspecFieldValidator(entrypoint)
     ];