Adding full support for IPIP Tunnel

To create ipip tunnel with netctl you need to provide pointopoint parameter for this command:
ifconfig tun0 10.0.0.1 netmask 255.255.255.252 __pointopoint__ _10.0.0.2_

This pull request provide this by adding `IP=staticp2p`
and aditional variable `PoinToPoint='10.0.0.2'`