Please add FreeBSD as a build target

Although I thought I remembered using ipscan on FreeBSD in the past, I may have been mistaken. I tried building the latest git code as well as 3.5.3 since that was the last working release before the switch to gradle. Neither one would work. I tried using the any and current targets, but neither ant nor gradle would correctly detect FreeBSD as the OS. I also tried using the prebuilt Linux binary in case that might work, but it didn't. So it would would be very helpful to add a FreeBSD build target.