udpate facebook SDK to 5.6

composer.json

@@ -67,7 +67,6 @@
     "doctrine/migrations": "^1.0.0",
     "doctrine/orm": "^2.4.0",
     "elasticsearch/elasticsearch": "~2.0",
-    "facebook/php-sdk": "~3.2.3",
     "firebase/php-jwt": "^3.0.0",
     "gedmo/doctrine-extensions": "~2.3.0",
     "goodby/csv": "^1.3.0",
@@ -119,7 +118,8 @@
     "zend/gdata": "~1.12.1",
     "alchemy/worker-bundle": "^0.1.6",
     "alchemy/queue-bundle": "^0.1.5",
-    "google/recaptcha": "^1.1"
+    "google/recaptcha": "^1.1",
+    "facebook/graph-sdk": "^5.6"
   },
   "require-dev": {
     "mikey179/vfsStream": "~1.5",