added missing quotes in YAML files

Author: fabpot

Tests/Fixtures/yaml/services6.yml

@@ -8,7 +8,7 @@ services:
     file: { class: FooClass, file: %path%/foo.php }
     arguments: { class: FooClass, arguments: [foo, '@foo', [true, false]] }
     configurator1: { class: FooClass, configurator: sc_configure }
-    configurator2: { class: FooClass, configurator: [@baz, configure] }
+    configurator2: { class: FooClass, configurator: ['@baz', configure] }
     configurator3: { class: FooClass, configurator: [BazClass, configureStatic] }
     method_call1:
         class: FooClass