travis does not report failed tests correctly

I just noticed now, that Travis only checks if the exit value of the test was 0. See for example build 39, which was reported as successful even though the survey test clearly failed. I am not able to see how to fix this easily (I am sure there is a way to get unittest to always return non-zero when test has failed).

Alternatively we could actually run the tests by simply executing "ctest" in travis as well? This way we would make absolutely sure that we are running the same tests on both cdash and travis..