Added pytest-faulthandler to Travis (#945)

.travis.yml

@@ -63,6 +63,7 @@ install:
       fi;
     - pip install pytest-xdist # multi-thread py.test
     - pip install pytest-cov # add coverage stats
+    - pip install pytest-faulthandler # activate faulthandler
 
     # Debugging helpers
     - uname -a