Add petra router to standalone mcrouter
Add petra router to standalone mcrouter

Summary: Title

Reviewed By: jmswen

Differential Revision: D5267418

fbshipit-source-id: 3a8c7015e124b4b225d8ff0c8db24478f82fa4e7

facebook/mcrouter,facebook/mcrouter,facebook/mcrouter,facebook/mcrouter