UC-53 Create a new module for Facebook v2+

Update the Facebook PHP and JS SDK's to the new version and create a new extension to implement the FB connect functionality through them.

https://wikia-inc.atlassian.net/browse/UC-53
There's no reason for any code outside FacebookClient to access the value in facebookAPI directly, and there isn't any  complexity around accessing this value, so I'm ok leaving out explicit setter/getters here.