Fixed NoDM configuration file, now dynamically generates instead of
copying a file.
Removed swap file because this shreds through MicroSDs and isn't needed
either.
* Added Docker support
- replaced necessity for devicemapper (through kpartx) by using parted and
losetup with offsets
- added Dockerfile
- added dependency for parted and grep
- added hints to README.md
- common: loop through unmounts, fix shellcheck warnings
* stage2: use debconf instead of console-setup patch. Fixes#41
