1.
https://github.com/facebook/facebook-php-sdk-v4
2.
https://www.sammyk.me/using-the-facebook-sdk-v4-without-composer
3.
http://stackoverflow.com/questions/32029116/facebook-sdk-returned-an-error-cross-site-request-forgery-validation-failed-th
4.
http://stackoverflow.com/questions/37498264/call-to-undefined-function-hash-equals-in-facebook-helpers-facebookredirectlog
