Updated Facebook URLs to include API version (2.0).

Removed references to the 'username' field which is no longer returned.  Updated
tests to reflect app scoped IDs.

[Facebook API 2.0](https://developers.facebook.com/docs/apps/upgrading) seems to be making an effort to make uniquely identifiable information unavailable to apps (presumably to reduce user tracking and such.)  The [Business Mapping API](https://developers.facebook.com/docs/apps/for-business) has been introduced to allow user tracking between apps published by the same business.

All this to say, username is no longer returned, and user ids are scoped to the app.  I don't know what the effect is on Facebook emails that include the user id (if that's even possible) since my primary email address is not my Facebook email address (and Facebook doesn't give me the option to make it primary.)