Adds a persistant message with the ``INFO`` level.

def persistant_info(request, message, extra_tags='', fail_silently=False, *args, **kwargs):
    """
    Adds a persistant message with the ``INFO`` level.
    """
    add_message(request, INFO_PERSISTENT, message, extra_tags=extra_tags,
                fail_silently=fail_silently, *args, **kwargs)