update travis to provide gfortran and disable osx (#176)
update travis to provide gfortran and disable osx (#176)

This change replaces fort77 with gfortran in the travis-ci instance,
and disables osx for now because there's no java 1.6 on travis' VMs.
OpenVnmrJ/OpenVnmrJ,OpenVnmrJ/OpenVnmrJ,OpenVnmrJ/OpenVnmrJ,OpenVnmrJ/OpenVnmrJ,OpenVnmrJ/OpenVnmrJ,OpenVnmrJ/OpenVnmrJ,OpenVnmrJ/OpenVnmrJ,OpenVnmrJ/OpenVnmrJ,OpenVnmrJ/OpenVnmrJ,OpenVnmrJ/OpenVnmrJ