debian/changelog: update for the 0.2 release pkg

This is meant for packaging the 0.2 tag
(81505fade42134e249cfe410125097820cc8e8b5).
debian: 0.2.1-1 package update

Includes all of the fairly minor bugfixes since 0.2. Also includes the
python-swiftclient dependency (which wasn't present in the package
before).
Merge pull request #162 from larsbutler/deb-pkg-0.2.1

Debian package for 0.2.1