add xunit to jenkins pretest

.jenkins/jenkins_pretest.sh

@@ -10,7 +10,7 @@ export PATH=/usr/local/miniconda2/bin:$PATH
 
 # Test flake8
 echo "===== Testing flake8"
-bin/theano-nose theano/tests/test_flake8.py || exit 1
+bin/theano-nose theano/tests/test_flake8.py --with-xunit --xunit-file=theano_pre_tests.xml || exit 1
 
 # Test documentation
 echo "===== Testing documentation build"