Remove pointless Debian support to simplify code

Packstack is incompatible to Debian in many places, therefore
supporting it in just one single place just makes no sense. If
at all, complete instead of very partial Debian support should
be introduced. Until such time it's easiest to support all the
different Fedora and RHEL derivatives by having no operating
system discriminator at all.

Partially discussed at:
https://bugzilla.redhat.com/show_bug.cgi?id=906269

Change-Id: I93cd4d25b0f85bae24c97be6ed91547dce1935d7
Merge "Remove pointless Debian support to simplify code"