disable osX on travis
disable osX on travis

TyberiusPrime/pysam,kyleabeauchamp/pysam,bioinformed/pysam,kyleabeauchamp/pysam,bioinformed/pysam,pysam-developers/pysam,TyberiusPrime/pysam,kyleabeauchamp/pysam,pysam-developers/pysam,pysam-developers/pysam,TyberiusPrime/pysam,TyberiusPrime/pysam,kyleabeauchamp/pysam,pysam-developers/pysam,TyberiusPrime/pysam,bioinformed/pysam,bioinformed/pysam,bioinformed/pysam,kyleabeauchamp/pysam