Dropping dedicated backports mirror handling, not needed anymore with the move of backports.d.o into ftp.d.o.

Adding check for ntfs-3g on the host system, precluding the initial ntfs binary filesystem support (Closes: #697793).

Using dpkg-divert in chroot_upstart script to handle upgrades of upstart during the build (Closes: #702537).

Correcting typo directory when dereferencing syslinux symlinks when building chrooted, thanks to Luigi Capriotti <l.capriotti@xbmc.org>.

The check protecting their addition was wrong. Also fix the actual keys
with the correct architecture instead of hardcoding i386.

Removing quotes around _CGI_CONFIG_APPEND to handle multiple parameters correctly on l-b-cgi frontend.

At least on armel with ext4, 5% turned out to not be enough in some use
cases. With 6% the failure was gone.

Harmonize handling of pre-existing gnupg dotfiles in chroot when handling fake signing keys for local repository.