message: fix error if claim value equals bool false
  Hasura expects claim value to be text. Without this fix, if the user_field value is false, the claim value is returned as boolean false. Hasura then triggers an error.
diff: @@ -17,7 +17,7 @@ module.exports = {
  return null;
  }
  - custom_claims['x-hasura-' + user_field.replace('_', '-')] = user[user_field] && user[user_field].toString();
  + custom_claims['x-hasura-' + user_field.replace('_', '-')] = user[user_field].toString();
  });
  const user_roles = user.user_roles.map(role => {
  