add function for persistent ulimit -n setting
add function for persistent ulimit -n setting

cvmfs-testing/cvmfs,trshaffer/cvmfs,DrDaveD/cvmfs,cvmfs-testing/cvmfs,djw8605/cvmfs,Moliholy/cvmfs,alhowaidi/cvmfsNDN,cvmfs/cvmfs,reneme/cvmfs,djw8605/cvmfs,alhowaidi/cvmfsNDN,Gangbiao/cvmfs,MicBrain/cvmfs,alhowaidi/cvmfsNDN,cvmfs/cvmfs,cvmfs-testing/cvmfs,reneme/cvmfs,Moliholy/cvmfs,djw8605/cvmfs,cvmfs/cvmfs,cvmfs-testing/cvmfs,Moliholy/cvmfs,cvmfs/cvmfs,reneme/cvmfs,DrDaveD/cvmfs,Moliholy/cvmfs,MicBrain/cvmfs,DrDaveD/cvmfs,cvmfs/cvmfs,reneme/cvmfs,cvmfs/cvmfs,DrDaveD/cvmfs,alhowaidi/cvmfsNDN,MicBrain/cvmfs,trshaffer/cvmfs,Moliholy/cvmfs,Gangbiao/cvmfs,DrDaveD/cvmfs,cvmfs-testing/cvmfs,DrDaveD/cvmfs,MicBrain/cvmfs,trshaffer/cvmfs,Gangbiao/cvmfs,alhowaidi/cvmfsNDN,trshaffer/cvmfs,djw8605/cvmfs,MicBrain/cvmfs,reneme/cvmfs,Gangbiao/cvmfs,DrDaveD/cvmfs,cvmfs/cvmfs,trshaffer/cvmfs,Gangbiao/cvmfs,djw8605/cvmfs