Travis CI example

To use CTest Extension module with Travis CI use the following template for the .travis.yml file:

language: cpp
compiler:
  - gcc
  - clang
env:
  - CTEST_MODEL=Experimental
  - CTEST_MODEL=Nightly
install:
  - wget -qO- http://www.cmake.org/files/v3.1/cmake-3.1.0-Linux-x86_64.tar.gz | tar xvz
script:
  - ./cmake-3.1.0-Linux-x86_64/bin/ctest -VV -S ./project_test.cmake -DCTEST_MODEL=$CTEST_MODEL -DCTEST_EMPTY_BINARY_DIRECTORY=FALSE