.travis.yml for gcc-5 compiler support on Travis CI

.travis.yml

sudo: required
script:
  - sudo unlink /usr/bin/gcc && sudo ln -s /usr/bin/gcc-5 /usr/bin/gcc
  - gcc --version
addons:
  apt:
    sources:
    - ubuntu-toolchain-r-test
    packages:
    - gcc-5
    - g++-5

For anybody else's sake: The default g++ in Trusty fully supports C++11 language features, but the libstdc++ that's installed alongside g++-5 is the first that's feature complete for C++11 library features.