debian: add debian/po

This file was dropped when I imported the debian directory, but looks
like a necessary file.  Without this patch, installing the created deb
package will fail.

Signed-off-by: MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp>
Signed-off-by: Liu Yuan <namei.unix@gmail.com>
gitignore: ignore automatically generated .8 files

Signed-off-by: Hitoshi Mitake <mitake.hitoshi@lab.ntt.co.jp>
Signed-off-by: Liu Yuan <namei.unix@gmail.com>
trivial: let git ignore .deb files

Generated .deb files should be ignored by git.

Signed-off-by: Hitoshi Mitake <mitake.hitoshi@lab.ntt.co.jp>
Signed-off-by: MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp>