installer: Do not distinguish between upstream and own packages anymore

That simply is too cumbersome to maintain e.g. when we introduce an
updated package that we were already using from upstream.

Signed-off-by: Sebastian Schuberth <sschuberth@gmail.com>
packages: Use only two spaces for indentation

This is for consistency with the XML package description files.

Signed-off-by: Sebastian Schuberth <sschuberth@gmail.com>