Fix AArch64 machines with no RAM latched lower than 1GB
Resolves: rhbz#1615969
Set http_path and http_url when HTTP booting
Hopefully slightly better error reporting in some cases
Better allocation of kernel+initramfs on x86_64 and aarch64
Resolves: rhbz#1572126
Signed-off-by: Peter Jones <pjones@redhat.com>
