Testing|hack, issue #1009: Update make kack environment
TestKill and TestMultipleContainers: run sleep instead of cat /bin/zero. fixes #737
Merge pull request #1010 from dotcloud/1009-testing-hack

Testing|hack, issue #1009: Update make hack environment
Merge pull request #1021 from errnoh/fix-test-filled-tmpfs

TestKill and TestMultipleContainers: run sleep instead of cat /bin/zero....
Add a script to create the docker-ut image

It's a fork of the mkimage-busybox.sh script and it adds socat to the
image. (socat being needed to add udp support, see #33).

This script, like mkimage-busybox.sh, probably only works on
Debian/Ubuntu.