.travis.yml: add h5md build test
.travis.yml: add h5md build test

MrTheodor/csg,MrTheodor/csg,junghans/csg,votca/csg,junghans/csg,junghans/csg,votca/csg,votca/csg,junghans/csg,MrTheodor/csg,MrTheodor/csg,MrTheodor/csg,junghans/csg,junghans/csg,votca/csg