add override to tools_jenkins meta tasks

docker/build/tools_jenkins/Dockerfile

@@ -7,4 +7,4 @@ 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' 

playbooks/roles/tools_jenkins/meta/main.yml

@@ -7,3 +7,4 @@ dependencies:
     jenkins_plugins: "{{ jenkins_tools_plugins }}"
     jenkins_version: "{{ jenkins_tools_version }}"
     jenkins_deb_url: "http://pkg.jenkins-ci.org/debian-stable/binary/jenkins_{{ jenkins_version }}_all.deb"
+    jenkins_custom_plugins: []