Remove root autobind search restriction, fix upgrade logging & error handling.
    
    There was no point in limiting autobind root to just search cn=config since
    it could always just modify its way out of the box, so remove the
    restriction.
    
    The upgrade log wasn't being created. Clearing all other loggers before
    we calling logging.basicConfig() fixes this.
    
    Add a global exception when performing updates so we can gracefully catch
    and log problems without leaving the server in a bad state.
    
    https://fedorahosted.org/freeipa/ticket/1243
    https://fedorahosted.org/freeipa/ticket/1254