C++11 & GTest 1.7 buildfix: don't depend on contextual bool conversion
C++11 & GTest 1.7 buildfix: don't depend on contextual bool conversion

GTest doesn't permit contextual conversion-to-bool until 1.8, so
explicitly convert to bool as a workaround.

paoloambrosio/cucumber-cpp,cucumber/cucumber-cpp,konserw/cucumber-cpp,muggenhor/cucumber-cpp,AbletonAppDev/cucumber-cpp,meshell/cucumber-cpp,konserw/cucumber-cpp,cucumber/cucumber-cpp,paoloambrosio/cucumber-cpp,paoloambrosio/cucumber-cpp,AbletonAppDev/cucumber-cpp,cucumber/cucumber-cpp,konserw/cucumber-cpp,AbletonAppDev/cucumber-cpp,muggenhor/cucumber-cpp,muggenhor/cucumber-cpp,meshell/cucumber-cpp,meshell/cucumber-cpp