Remove unused/redundant script sections

Conflicts:
	wheezy-stage2
Reduce image size

We're only creating a minimal install, so it doean't need to be as big
as for a full image.
Configure timezone in stage2

Setting timezone values in debconf in stage3 is no good because tzdata
is already installed by then, therefore the changes don't take effect.

Conflicts:
	wheezy-stage2
Fix sudo in image export

Because attach_image_to_nbd calls sudo in the background, this can lead
to mixed up output when prompting for passwords.  Calling sudo -v
beforehand prevents this.
Berlin timezone & update comment
Use DEBIAN_FRONTEND=noninteractive

Prevents errors about loading up other interactive frontends

Conflicts:
	wheezy-stage2
Allow hostname to be set from dhcp.

Requires workaround for dhcp client scripts. See
http://blog.schlomo.schapiro.org/2013/11/setting-hostname-from-dhcp-in-debian.html
for more details.

Conflicts:
	wheezy-stage2
add untested to apt sources
Remove stage4 scripts.

We're only producing a minimal image, so these are unnecessary.

Conflicts:
	wheezy-stage4-lxde-edu
Explicitly unmount partitions after copying /boot

When this was left to universal_cleanup there appeared to be a race
condition where boot would still be busy when attempting to unmount it.
The unmount would therefore fail.  This led to the nbd being
disconnected without the writes to the boot partition being committed,
resulting in an empty /boot in the resulting image.
Set gpu_mem to 16 (the minimum).

Since we're aiming these images at server-style deployments, defaulting
the gpu_mem to the minimum makes sense
Remove temporary setting of root password

There's no point setting it, only to clear it later on.

Conflicts:
	wheezy-stage2