Fixes issues with mounting subdirectories of /mnt in container.

Tested with
mkdir /mnt/data
docker run -v /mnt/data:/mnt/data  -t ubuntu:12.10 touch /mnt/data/bar

Expected /mnt/data/bar on host.
check return value of syscall.Chdir when changing working directory
Rename mkimage-debian.sh to mkimage-debootstrap.sh to more clearly reflect its true function
Refactor mkimage-debootstrap.sh to be much more full-featured

This includes the following:
- options to control certain parameters
- an option specifically for creating tarballs directly, esp. for dockerbrew
- the addition of the updates and security repositories for Debian images
- the addition of the universe, updates, and security repositories for Ubuntu images
- more correct tagging of Debian images
- tagging of Ubuntu image versions (12.04, 12.10, etc) and latest tag for LTS
Try a different presentation of infrastructure documentation.
make copy paste user friendly

copying only the first line killed my sources.list file
c&p improvement for 13.04

first line killed sources list
Add initial init scripts library, including systemd, sysvinit, upstart, and openrc
Update CHANGELOG.md
Add Stackbrew.
Merge pull request #2253 from jpetazzo/infrastructure-docs

Try a different presentation of infrastructure documentation.
clean split between errors and output. JSON output always valid
Clean up build warnings. Remove redundant files.
Hack: don't run integration tests in /var/lib/docker/unit-tests; add missing cleanups in a few tests
Hack: fix tests which didn't cleanup properly
Use heredoc to make expect script more clear
Merge pull request #2283 from tmc/master

Make mkimage-arch.sh a little more clear
Increase readbility of unit tests by using mkRuntime everywhere
hack: encode the name of the current test in temporary directories, for easier tracking

Conflicts:
	utils_test.go
Merge pull request #2282 from shykes/fix-tests

Tests: Cleanup the test suite