One of the lines wasn't quite unneccesary.

.travis.yml

@@ -2,6 +2,7 @@ language: cpp
 compiler:
  - gcc
 before_install:
+ - sudo add-apt-repository ppa:ubuntu-toolchain-r/test -y
  - sudo apt-get -qq update
  - sudo apt-get -qq install libgtest-dev g++-4.8 xorg-dev libglu1-mesa-dev
  - sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-4.8 90