Switch to puppetlabs-xinetd

This one is a little complex because in parallel to merging this it needs someone to drop the existing xinetd submodule and clone over the puppetlabs-xinetd one to theforeman's account.

Here is the output of /etc/xinetd.d/tftp on a run with the changes and new xinetd module:

[root@localhost foreman-installer]# cat /etc/xinetd.d/tftp 
# This file is being maintained by Puppet.
# DO NOT EDIT

service tftp
{
        port            = 69
        disable         = no
        socket_type     = dgram
        protocol        = udp
        wait            = yes
        user            = root
        group           = root
        server          = /usr/sbin/in.tftpd
        bind            = 0.0.0.0
        server_args     = -v -s /var/lib/tftpboot/ -m /etc/tftpd.map
        per_source      = 11

        cps             = 100 2
        flags           = IPv4

}