Revert "Upgrade to newer source format. (#135)"
This reverts commit f89cdbde0872a055f92b9c1879eef4be454af5fd.
This change breaks building with dpkg-buildpackage, which we use in
travis-ci. If anyone wants to reintroduce it, either figure a way to
build deb packages properly in travis, or make it pass in some other
way.
