Add missing permissions

[andredaniel]

When I was trying to cancel and refund transactions via application I came acrros two missing permission types.

$authorization = new \PagSeguro\Domains\Requests\Authorization();

$authorization->addPermission(\PagSeguro\Enum\Authorization\Permissions::REFUND_TRANSACTIONS);
$authorization->addPermission(\PagSeguro\Enum\Authorization\Permissions::CANCEL_TRANSACTIONS);