New VPN server supports vpnc

This helps doing away with a lot of ugly kernel hacks that had to be employed in order to get the Cisco client working with recent kernels and such. It also allows for a really straightforward installation and configuration process. This brings VPN connections to the UA to a whole new level!

Instruction on how to use the new server are to be found at the official UA sites (for Windows) (Update: this page was removed) and on the Linux/Mac OS Wiki here.