Twitter: Added Email to ArrayHydrator object

Twitter Provider was missing the email key, as such even if the app has email permission it would report the email as null.

src/OAuth1/Provider/Twitter.php

@@ -60,6 +60,7 @@ public function getIdentity(AccessTokenInterface $accessToken)
         $hydrator = new ArrayHydrator([
             'id' => 'id',
             'name' => 'fullname',
+            'email' => 'email',
             'screen_name' => 'username',
             'profile_image_url_https' => 'pictureURL'
         ]);