old-style dpkg foreign architecture adding for tests

Looks like the travis service runs on Ubuntu in a version which has dpkg
with an earlier interface implementation, so lets try if we can't make
the framework work with this dpkg version as well.

Git-Dch: Ignore
configurable compression for testcases

Compressing files in 4 different styles eats test-time for no practical
gain if we don't test them explicitly, so default to just building 'gz'
compressed files as it is the simplest compression algorithm supported

Git-Dch: Ignore