Make requirements stricter (required packages instead of recommended
packages) and remove requirements that are no longer needed. The
previous requirements caused failures in manual testing and possibly
some gating failures as well.
Related: https://pagure.io/fedora-ci/general/issue/206
Also, drop unneeded legacy Makefile's and PURPOSE files,
and explicitly require gcc.rpm, which is not installed
on the CI workers by default any more it seems.
