Ticket #633 - allow nsslapd-nagle to be disabled, and also tcp cork
    
    https://fedorahosted.org/389/ticket/633
    Reviewed by: nhosoi (Thanks!)
    Branch: master
    Fix Description: Instead of hard-coded enable_nagle = 1 in the connection
    code, use the server config nsslapd-nagle setting.  The default is on
    on linux.  Also make the tcp cork in connection_dispatch_operation() depend
    on the nagle setting - if nagle is enabled, then enable tcp cork, otherwise,
    disable tcp cork too.
    Platforms tested: RHEL6 x86_64
    Flag Day: no
    Doc impact: Yes - document new config parameter