.travis.yml: install newer cmake for gmx-5
.travis.yml: install newer cmake for gmx-5

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