Add no-attrs-snapshot rule to recommended

Author: chadhietala

config/recommended.js

@@ -17,6 +17,7 @@ module.exports = {
     'ember-best-practices/require-dependent-keys': 2,
     'ember-best-practices/no-lifecycle-events': 2,
     'ember-best-practices/no-timers': 2,
-    'ember-best-practices/no-unguarded-document': 2
+    'ember-best-practices/no-unguarded-document': 2,
+    'ember-best-practices/no-attrs-snapshot': 2
   }
 };