Fix 32-bit binary package installs on 64-bit OS

This fixes #6303. It also forces a change in SLS for apt-based systems,
to avoid a name collision with the 64-bit version of the package. 32-bit
binary packages must now be referred to using pkgname:arch, as they
appear in dpkg --list.

Conflicts:
	salt/modules/pkg_resource.py
Docstring tweak for pull req #6461