Newer cmake for Travis Linux

cmake/travis_before_install_linux.sh

 
 sudo add-apt-repository -y ppa:zoogie/sdl2-snapshots
 sudo add-apt-repository -y ppa:ubuntu-toolchain-r/test
-sudo add-apt-repository -y ppa:kalakris/cmake
+sudo add-apt-repository -y ppa:smspillaz/cmake-2.8.12
 sudo add-apt-repository -y 'deb http://llvm.org/apt/precise/ llvm-toolchain-precise-3.5 main'
 sudo apt-get -qq -y update