jenkins.sh: Run python bits in a virtualenv

because we may not have pep8 installed at the system level

jenkins.sh

@@ -8,6 +8,11 @@ rm -f olm-*.tgz
 make lib
 make test
 
+virtualenv env
+. env/bin/activate
+pip install pyyaml
+pip install pep8
+
 ./python/test_olm.sh
 pep8 -v python