add run command to start jenkins

docker/build/tools_jenkins/Dockerfile

@@ -7,4 +7,6 @@ RUN apt-get update
 ADD . /edx/app/edx_ansible/edx_ansible
 WORKDIR /edx/app/edx_ansible/edx_ansible/docker/plays
 COPY docker/build/tools_jenkins/ansible_overrides.yml /
-RUN PYTHONUNBUFFERED=1 /edx/app/edx_ansible/venvs/edx_ansible/bin/ansible-playbook -v jenkins_tools.yml -i '127.0.0.1,' -c local -e@/ansible_overrides.yml -vv -t 'install' 
+RUN PYTHONUNBUFFERED=1 /edx/app/edx_ansible/venvs/edx_ansible/bin/ansible-playbook -v jenkins_tools.yml -i '127.0.0.1,' -c local -e@/ansible_overrides.yml -vv -t 'install'
+
+CMD /bin/su -l jenkins --shell=/bin/bash -c "/usr/bin/daemon -f --name=jenkins --inherit --env=JENKINS_HOME=/edx/var/jenkins --output=/var/log/jenkins/jenkins.log --pidfile=/var/run/jenkins/jenkins.pid -- /usr/bin/java  -jar /usr/share/jenkins/jenkins.war --webroot=/var/cache/jenkins/war --httpPort=8080 --ajp13Port=-1"