Replace GCC 4.8.0 (pre-final) with 4.8.1 (final) for FC and SLC6

Signed-off-by: David Abdurachmanov <davidlt@cern.ch>
Merge pull request #165 from davidlt/config-map-gcc-481

Replace GCC 4.8.0 (pre-final) with 4.8.1 (final) for FC and SLC6