install-spotify: libmp3lame0: various fixes

Dont hardcode version. Use a temporary repo instead of clobbering
user's environment with the packman repo.
install-spotify: download_spotify_make: Dont reuse old tarball
install-spotify: download_debs: get all packages, keep previous dl.

In order to generate the builddeps we need a srpm package - there
seem to no equivalent of yum-builddep which can get the buildeps
for a spec file in the zypper universe.

Building a srpm means that both packages unfortunately are needed,if
we want to stick to rpm semantics.

Keeping the old packages in the dl area means that they will be reused
onlater builds.
install-spotify: install_builddeps: bad path, allow zypper error.

zypper returns an irrelevant error code if all deps already are in
place - this can and should be ignored. Fix a bad path.
install-spotify: build-rpm: Handle QA_RPATHS, fix bad path +  error msg.

Once again upstream introduces a bad rpath with version 0.9.1. Fix
using QA_RPATHS environment variable. Fix bad path in rpm_path and
let error message contain what's actually failing.
install-spotify: keep  quiet

Lot's of output from whet and rpmbuild obscures other important
warnings