CM-1607 (Mark/Cory) Add wrappers and helpers for Windows Firewall API

@markbenvenuto @corymintz And now here comes the giant pull request with the serious Win32 black magic: calling COM interfaces from Go.  This contains everything needed to add a firewall rule, query an existing firewall rule, and check whether or not a program is allowed through the firewall on a given port.  Each of the above was tested with a small test program, which has not been checked in.