Update pcbsd-build, add options to build TrueOS images, which
will be much much smaller than PC-BSD images, since they wont ship
with Xorg and other packages.
Use the correct grub.cfg for PC-BSD / TrueOS media
Set correct name on TrueOS ISO file
Use different poudriere world names when doing trueos builds
Mark TrueOS media with flag so we know that no desktop packages are
available on it