Improve hyperkit/osx testing

Address #954:
- Pull hyperkit and vpnkit binaries from CI
- Use vpnkit instead of vmnet
- Add hyperkit-test test target

Signed-off-by: Robb Kistler <robb.kistler@docker.com>

hyperkit.sh

@@ -3,22 +3,21 @@
 set -e
 
 KERNEL="alpine/kernel/x86_64/vmlinuz64"
-INITRD="alpine/initrd.img"
+: ${INITRD:="alpine/initrd.img"}
 CMDLINE="earlyprintk=serial console=ttyS0"
 
 [ -f disk.img ] || dd if=/dev/zero of=disk.img bs=1m count=256
 
 MEM="-m 1G"
 SMP="-c 1"
-NET=""
-if (( $EUID != 0 )); then
-    printf "Need to run as root to get networking!\n\n"
-    exit 1
-fi
-NET="-s 2:0,virtio-net"
+SLIRP_SOCK=$(mktemp)
+NET="-s 2:0,virtio-vpnkit,path=$SLIRP_SOCK"
 IMG_HDD="-s 4,virtio-blk,disk.img"
 PCI_DEV="-s 0:0,hostbridge -s 31,lpc"
 RND="-s 5,virtio-rnd"
 LPC_DEV="-l com1,stdio"
 
-hyperkit.git/build/com.docker.hyperkit -A $MEM $SMP $PCI_DEV $LPC_DEV $NET $IMG_HDD $RND -u -f kexec,$KERNEL,$INITRD,"$CMDLINE"
+hyperkit.bin/com.docker.slirp --ethernet $SLIRP_SOCK &>/dev/null &
+trap "kill $!; rm $SLIRP_SOCK" EXIT
+
+hyperkit.bin/com.docker.hyperkit -A $MEM $SMP $PCI_DEV $LPC_DEV $NET $IMG_HDD $RND -u -f kexec,$KERNEL,$INITRD,"$CMDLINE"