Add support for Facebook AppSecret-Proof, bump version to v0.1.5

See [https://developers.facebook.com/docs/reference/api/securing-graph-api/](https://developers.facebook.com/docs/reference/api/securing-graph-api/)] and [https://github.com/jaredhanson/passport-facebook/issues/62](https://github.com/jaredhanson/passport-facebook/issues/62) for more details.

This pull request includes a clone of the support added to the facebook-token package. Let me know if you have any questions - thanks!