Add new methods to FB driver.

Signed-off-by: Ben Corlett <bencorlett@me.com>

src/League/OAuth2/Client/Provider/Facebook.php

@@ -42,4 +42,19 @@ class Facebook extends IdentityProvider
 
         return $user;
     }
+
+    public function userUid($response, \League\OAuth2\Client\Token\AccessToken $token)
+    {
+        return $response->id;
+    }
+
+    public function userEmail($response, \League\OAuth2\Client\Token\AccessToken $token)
+    {
+        return isset($response->email) && $response->email ? $response->email : null;
+    }
+
+    public function userScreenName($response, \League\OAuth2\Client\Token\AccessToken $token)
+    {
+        return array($response->first_name, $response->last_name);
+    }
 }