Use time.Time.UnixNano in LeaseToken
Use time.Time.UnixNano in LeaseToken

Serialize the expiration time inside the token as UnixNano, to be consistent with the
serialization used inside LeaseDB

cvmfs/cvmfs,cvmfs/cvmfs,cvmfs/cvmfs,DrDaveD/cvmfs,DrDaveD/cvmfs,DrDaveD/cvmfs,DrDaveD/cvmfs,cvmfs/cvmfs,cvmfs/cvmfs,cvmfs/cvmfs,DrDaveD/cvmfs,cvmfs/cvmfs,DrDaveD/cvmfs,DrDaveD/cvmfs