vpcs 0.6 new formula

Project description:
The VPCS can simulate up to 9 PCs. You can ping/traceroute them, or
ping/traceroute the other hosts/routers from the virtual PCs when you
study the Cisco routers in the Dynamips. VPCS is not the traditional PC,
it is just a program running on the Linux or Windows, and only few
network commands can be used in it. But VPCS can give you a big hand
when you study the Cisco devices in the Dynamips. VPCS can replace the
routers or VMware boxes which are used as PCs in the Dynamips network.
Can this test be modified to do something more substantial than e.g. `--version` or `--help`? See `cmake.rb` for an example of an application formula with a good test and `tinyxml2.rb` for an example of a library formula with a good test. Thanks!