Update CAS to use Facebook Graph API 2.1

I just got alert from Facebook developer console that CAS uses Facebook Graph API 2.0 call during Social login and it is necessary to update it to use API 2.1:

JBoss Developer website has been making recent API calls to Graph API v2.0, which will reach the end of the 2-year deprecation window on Monday, August 8, 2016. Please migrate all calls to v2.1 or higher in order to avoid potential broken experiences.

We recommend using our new Graph API Upgrade Tool to see which of your calls are affected by this change as well as any replacement calls in newer versions. You can also use our changelog to see the full list of changes.