compiler version in travis.yml changed back to 4.8

.travis.yml

@@ -20,12 +20,12 @@ before_install:
    - sudo add-apt-repository ppa:ubuntu-toolchain-r/test -y
    - sudo add-apt-repository ppa:kalakris/cmake -y
    - sudo apt-get update -qq
-   - sudo apt-get install -qq gcc-4.91
+   - sudo apt-get install -qq gcc-4.8
    - sudo apt-get install -qq --no-install-recommends build-essential cmake python-lxml graphviz doxygen wget
    - wget http://security.ubuntu.com/ubuntu/pool/main/c/check/check_0.9.10-6ubuntu3_amd64.deb
    - sudo dpkg -i check_0.9.10-6ubuntu3_amd64.deb
    - sudo pip install cpp-coveralls
-   - sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.91 20
+   - sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.8 20
    - sudo update-alternatives --config gcc
 script: 
    - mkdir -p build