Use Docker instead of Vagrant for generate images

Fixes #2

tools/qemu-debian-img/setup.sh

@@ -0,0 +1,17 @@
+#!/bin/sh -eux
+# Copyright 2018 Mikhail Klementev. All rights reserved.
+# Use of this source code is governed by a AGPLv3 license
+# (or later) that can be found in the LICENSE file.
+TMPDIR=$1
+chroot $TMPDIR /bin/sh -c 'useradd -m user'
+sed -i 's/root:\*:/root::/' $TMPDIR/etc/shadow
+sed -i 's/user:!!:/user::/' $TMPDIR/etc/shadow
+echo auth sufficient pam_permit.so > $TMPDIR/etc/pam.d/sshd
+sed -i '/PermitEmptyPasswords/d' $TMPDIR/etc/ssh/sshd_config
+echo PermitEmptyPasswords yes >> $TMPDIR/etc/ssh/sshd_config
+sed -i '/PermitRootLogin/d' $TMPDIR/etc/ssh/sshd_config
+echo PermitRootLogin yes >> $TMPDIR/etc/ssh/sshd_config
+
+echo '#!/bin/sh' > $TMPDIR/etc/rc.local
+echo 'dhclient' >> $TMPDIR/etc/rc.local
+chmod +x $TMPDIR/etc/rc.local