add _logistic_function() closure to _common
add _logistic_function() closure to _common

djw8605/cvmfs,alhowaidi/cvmfsNDN,Moliholy/cvmfs,trshaffer/cvmfs,DrDaveD/cvmfs,Gangbiao/cvmfs,cvmfs/cvmfs,DrDaveD/cvmfs,trshaffer/cvmfs,DrDaveD/cvmfs,djw8605/cvmfs,reneme/cvmfs,Moliholy/cvmfs,reneme/cvmfs,cvmfs/cvmfs,alhowaidi/cvmfsNDN,DrDaveD/cvmfs,reneme/cvmfs,Gangbiao/cvmfs,Moliholy/cvmfs,reneme/cvmfs,DrDaveD/cvmfs,reneme/cvmfs,cvmfs/cvmfs,Moliholy/cvmfs,cvmfs/cvmfs,alhowaidi/cvmfsNDN,DrDaveD/cvmfs,djw8605/cvmfs,trshaffer/cvmfs,cvmfs/cvmfs,djw8605/cvmfs,cvmfs/cvmfs,Gangbiao/cvmfs,alhowaidi/cvmfsNDN,Moliholy/cvmfs,DrDaveD/cvmfs,cvmfs/cvmfs,Gangbiao/cvmfs,djw8605/cvmfs,trshaffer/cvmfs,alhowaidi/cvmfsNDN,Gangbiao/cvmfs,trshaffer/cvmfs