Make RPM building more similar to how RPMs will be built in koji.
This downloads the specfile from github at the given commit, appends
the commit sha to the specfile and uses spectools to download the
correct sources from github.
This should be equivalent to what is done in the makefile, the only
behavioral difference is that the rpms are now versioned based on
the git sha they are built from.
The main purpose of this change is to avoid any differences between
the CI and the real RPMs due to bugs in the Makefile. Correctly
versioned RPMs will also be handy for testing/debugging/deployment.
Signed-off-by: Tom Gundersen <teg@jklm.no>
