Add serializable_hash with nil options, to be squashed

Author: bf4

test/serializer_builder_test.rb

@@ -11,7 +11,8 @@ def setup
       end
 
       def test_builder_delegates_serializable_hash_to_the_adapter
-        assert_equal @adapter.serializable_hash, @builder.serializable_hash
+        options = nil
+        assert_equal @adapter.serializable_hash(options), @builder.serializable_hash(options)
       end
 
       def test_builder_delegates_to_json_to_the_adapter