TravisCI: First dirty add of OSX test
TravisCI: First dirty add of OSX test

This is not expected to work; just triggering a CI job to see what kinds of errors are generated...

MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3