Added missing 'http_url_to_repo' property to Project model

Author: m4tthumphrey

lib/Gitlab/Model/Project.php

@@ -25,7 +25,8 @@ class Project extends AbstractModel
         'wiki_enabled',
         'created_at',
         'greatest_access_level',
-        'ssh_url_to_repo'
+        'ssh_url_to_repo',
+        'http_url_to_repo'
     );
 
     public static function fromArray(Client $client, array $data)