Package alterator-net-pptp: Information

- implemented --clamp-mss-to-pmtu autosetup (closes: #26124)
  + should help when a remote host pings and works ok from gateway
    setup using this module but a workstation behind it will ping
    that remote host but timeout on e.g. http due to oversized packets
  + you might need to explicitly enable /etc/net firewall by adding
    CONFIG_FW=yes to /etc/net/ifaces/default/options; if that's ever
    needed, please amend http://bugzilla.altlinux.org/26124

- disabled Van Jacobson compression by default (reported symptom:
  ICMP ping would work just fine, while HTTP HEAD would get stuck;
  forward port of 0.5.10-alt1)
- updated Packager:
- added an Url:

- use setsid for ifup comand.