Speed-up travis CI build using contained-based infrastructure
Speed-up travis CI build using contained-based infrastructure

See http://docs.travis-ci.com/user/migrating-from-legacy

thewtex/python-cmake-buildsystem,python-cmake-buildsystem/python-cmake-buildsystem,thewtex/python-cmake-buildsystem,davidsansome/python-cmake-buildsystem,chuckatkins/python-cmake-buildsystem,adrianbroher/python-cmake-buildsystem,jcfr/python-cmake-buildsystem