xen recipe: add compile time dependency for xz (non-native).
init-boot-hype: add support for aufs for copy-on-write union mount, falling back to unionfs if aufs mount fails.
init-boot-hype: allow user to resume on fatal error.
xen recipe: include xenwatchdogd in xen-watchdog package and misc cleanup.
kernel: add aufs support for 3.8 kernel by specifying SRCREVs for newer sugarbay meta/machine reference and appending kernel feature.