FIX: 620 - reuse `cvmfs_preload` discovery/building routine
FIX: 620 - reuse `cvmfs_preload` discovery/building routine

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