Resolves: rhbz#1184021
--make-pxe-live target generate live squashfs and initrd for pxe boot.
Also generates pxe config template.
--make-ostree-live is used for installations of Atomic Host. Additionally to
--make-pxe-live it ensures using deployment root instead of physical root of
installed disk image where needed. Atomic installation needs to be virt
installation with /boot on separate partition (the only way supported by
Anaconda currently). Content of boot partition is added to live root fs so that
ostree can find deployment by boot configuration.
