Purge samba.  It gets into device image, because some package
recommends winbind, which has samba-package as a dependency.
We do not need either.
Disable some functionality in update-notifier-common package
(just removing the package would be nice, but ttf-mscorefonts-installer
package depends on it.
Remove btrfs-tools, it slows down boot (by about 2%) and is not used.