client: Fix error when a RequestException has no status_code

It's not available for instance for the following RequestException:

ConnectionError(ProtocolError('Connection aborted.', error("(104, 'ECONNRESET')",)),)

Author: underyx

sentry_auth_gitlab/client.py

@@ -22,7 +22,7 @@ def _request(self, path, access_token):
         try:
             req = http.get(url, headers=headers)
         except RequestException as e:
-            raise GitLabApiError(unicode(e), status=e.status_code)
+            raise GitLabApiError(unicode(e), status=getattr(e, 'status_code', None))
         return json.loads(req.content)
 
     def get_user(self, access_token):