added -f and a note about enabling VTx

Signed-off-by: Erik Weber <erikw@apache.org>
(cherry picked from commit 4da17a74ce27dd1e8e911a0787b2398a52efa47f)
Signed-off-by: Erik Weber <erikw@apache.org>
Updated CentOS version number to 6.5 (from 6.4)