fix for environment

.travis.yml

@@ -2,9 +2,13 @@ language: cpp
 
 sudo: false
 
+compiler:
+  - gcc
+
 env:
-  - CXX=g++-4.9
-  - CXX=g++-4.8
+  - COMPILER=g++-4.8
+  - COMPILER=g++-4.9
+  - COMPILER=g++-5
 
 addons:
   apt:
@@ -22,13 +26,13 @@ before_script:
   - pip install --user git+git://github.com/eddyxu/cpp-coveralls.git
 
 script:
-  - make
+  - make CXX=$COMPILER
   - ./json_unit "*"
   - valgrind --error-exitcode=1 --leak-check=full ./json_unit
 
 after_success:
   - make clean
   - touch src/json.hpp
-  - make json_unit CXXFLAGS="-fprofile-arcs -ftest-coverage -std=c++11"
+  - make json_unit CXXFLAGS="-fprofile-arcs -ftest-coverage -std=c++11" CXX=$COMPILER
   - ./json_unit "*"
   - coveralls --exclude test/catch.hpp --exclude test/unit.cpp --include src/json.hpp --gcov-options '\-lp' --gcov 'gcov-4.9'