scram-project-build: temporary download cmssw-config as tarball

Bootstrap needs to be rebuilt for Fedora 18 and SLC6 architectures
to include a new zlib package w/ version symbols compiled in. Until
that fetch cmssw-config as tarball.

Signed-off-by: David Abdurachmanov <davidlt@cern.ch>
scram-project-build: fix config directory name

Signed-off-by: David Abdurachmanov <David.Abdurachmanov@cern.ch>