[bugfix] adapt travis config to match travis update:
[bugfix] adapt travis config to match travis update:

https://github.com/travis-ci/travis-ci/issues/8552

dyoussef/s2p,MISS3D/s2p,carlodef/s2p,dyoussef/s2p,MISS3D/s2p,MISS3D/s2p,dyoussef/s2p,MISS3D/s2p,carlodef/s2p,mnhrdt/s2p,mnhrdt/s2p,dyoussef/s2p