scripts to run with the framework of run_generic_tarball.sh

script create_powheg_tarball.sh is used to create a tar balll that contains powheg executable, grid files, powheg input cards, and a script runcmsgrid.sh that could be run by run_generic_tarball.sh.
runcmsgrid_powheg.sh is the template of runcmsgrid.sh. This script must exist in the working directory when the tar ball is being created.

Both scripts are run after "cmsenv" is set.