cvmfs_config - modify checks for OSXFUSE
cvmfs_config - modify checks for OSXFUSE

* Not finding the /dev/osxfuse0 character device should be a warning not
  an error
* If /Library/Filesystems/osxfuse.fs doesn't exist, OSXFUSE hasn't been
  installed. This should be an error

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