fix multi-arch breaking

Debian has added multi-arch support so you can install packages for other
architectures, and when enabled, packages are differentiated by
'packagename:arch'

The dpkg-query format string '${Package}' displays a short-name, where
'${binary:Package}' displays the architecture 'tag'
code cleanup

cleaned up code to fit on 80 char lines
added test for multi-arch support

- dpkg-query doesn't recognize 'binary:Package' as a format variable
- if dpkg --print-foreign-architectures fails, change to old format
cleaner way to hide output from the command

cleaner than writing to a pipe I never access, woops
fixed redirecting command output to null

did not test the last commit, sorry.
Merge pull request #137 from cpbills/master

Debian multi-arch support fix