build-debian: Add "-r" option for releases; fix changelog logic

"-r" will build a PPA release ("stoken-0.6-1ppa1") instead of a snapshot
like "stoken-0.6~20140621093411-1ubuntu1".

Also, we will just autogenerate a new changelog instead of pretending
that the existing debian/changelog is up to date.  The real Debian
changelog will live in collab-maint.

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
examples: Add new qr-encode.sh script

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>