Do not chmod +s chvt: instead, rely on sudo

The SUID flag may be lost on update, and relying on sudo is
slightly more secure.

We create a file in /etc/sudoers.d/ : these files are sourced by
default since sudo 1.7.2p1-1 (Ubuntu 10.04 lucid, Debian squeeze).

Fixes #723.
ubuntu/bootstrap: Patch debootstrap so that it retries downloads

It retries 10 times, which is arguably too many times, but that
should be better than the current behaviour.

Applies cleanly on git HEAD and debootstrap 1.0.61. I will try to
upstream that modification.

Test:
 - Start installer, regularly run `sudo pkill wget` and check
   that the installation still proceeds.
ubuntu/bootstrap: mv -f
installer/ubuntu/bootstrap: Check if patch applies cleanly

Fallback on original version if it fails.
Merge pull request #1026 from drinkcat/deboostrap-retry

ubuntu/bootstrap: Patch debootstrap so that it retries downloads
Use github redirect to avoid certificate issues.

Possibly fixes #1033.
Fix permissions with the indirect installer cache.
targets/*: Blacklist selected releases/distros.

We use exit status 99 to indicate that a given combination is
unsupported (so we can detect it in tests).
targets/lxde: Do not install network-manager

Affects mainly Debian wheezy/jessie: When the chroot is terminated,
network-manager is killed, which brings down the wifi connection.

Does not hurt to specify it on non-Debian.
chromium: Debian has no chromium package for ARM. Sorry.

Also fix Debian package name (chromium-browser is an alias
on wheezy only).
test/39-alltargets: Test if all targets can at least be installed.

*common is blacklisted, as well as a few other lucky few.
edit-chroot: sync filesystem after backup is completed

Make sure that the data is actually on the physical device.
Merge pull request #1036 from drinkcat/backup-sync

edit-chroot: sync filesystem after backup is completed
targets/kali: Mark relevant targets as unsupported (same as wheezy).
Fix issues with bad cache after failed installer downloads.
Fix after review.
test/alltargets: Move from 39 to x0, so we run it on demand only.
Merge pull request #1042 from drinkcat/alltargets

Test all targets on all releases
audio: Relax matching rules for sbc package on wheezy

Some mirrors escape `+` as `%2b` in the URL, which causes the
regex not to match. Relax the regex so that we do not match the
`+` (that was probably overcautious in the first place).

Fixes #1043.
Merge pull request #1044 from drinkcat/wheezy-sbc-relax-match

audio: Relax matching rules for sbc package on wheezy