Use install_prereqs in tests

jenkins/test.sh

@@ -48,13 +48,8 @@ fi
 export PIP_DOWNLOAD_CACHE=/mnt/pip-cache
 
 source /mnt/virtualenvs/"$JOB_NAME"/bin/activate
-pip install -q -r pre-requirements.txt
-yes w | pip install -q -r requirements.txt
-
-bundle install
-
-npm install
 
+rake install_prereqs
 rake clobber
 rake pep8 > pep8.log || cat pep8.log
 rake pylint > pylint.log || cat pylint.log