add simple implementation of low-speed limit test (might still be flakey due to dependence on timeout values)
add simple implementation of low-speed limit test (might still be flakey due to dependence on timeout values)

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