Ticket #47669 - Retro Changelog Plugin accepts invalid value in nsslapd-changelogmaxage attribute
    
    Description: Converted parse_duration to the private api and applied the
    following config attributes.
      cn=changelog5,cn=config
        nsslapd-changelogmaxage
        nsslapd-changelogtrim-interval
        nsslapd-changelogcompactdb-interval
      cn=Retro Changelog Plugin,cn=plugins,cn=config
        nsslapd-changelogmaxage
    These config attributes take unsigned integer as well as digit[SsMmHhDdWw].
    Other input are logged in the error log and the invalid value is ignored.
    
    https://fedorahosted.org/389/ticket/47669
    
    Reviewed by rmeggins@redhat.com (Thank you, Rich!)