cmsBuild: replace ambiguous -i to --info for RPM

The following change required for newer version of RPM. `rpm' is
now a front-end handling arguments and calling different back-ends.
-i is supported for a couple of back-ends, thus making it ambiguous
to front-end.

Signed-off-by: David Abdurachmanov <davidlt@cern.ch>
Merge pull request #59 from davidlt/support-new-rpm

cmsBuild: replace ambiguous -i to --info for RPM