another fix for travis

.travis.yml

@@ -22,6 +22,7 @@ script:
 
 after_success:
   - make clean
+  - touch src/json.hpp
   - make json_unit CXXFLAGS="-fprofile-arcs -ftest-coverage -std=c++11"
   - ./json_unit
   - coveralls --exclude test/catch.hpp --exclude test/unit.cpp --include src/json.hpp --gcov-options '\-lp' --gcov 'gcov-4.9'