Quick stub rabbitmq docker container

Builds, runs very basically - useful for CI but not fully integrated
with other systems.

docker/build/rabbitmq/Dockerfile

+FROM edxops/precise-common:latest
+MAINTAINER edxops
+
+USER root
+ADD . /edx/app/edx_ansible/edx_ansible
+WORKDIR /edx/app/edx_ansible/edx_ansible/docker/plays
+
+# Role is currently untagged
+RUN /edx/app/edx_ansible/venvs/edx_ansible/bin/ansible-playbook rabbitmq.yml -c local \
+   -i '127.0.0.1,'
+
+USER rabbitmq
+# TBD what we want to run rabbit under
+EXPOSE 15672 5672

docker/plays/rabbitmq.yml

+- name: Deploy rabbitmq
+  hosts: all
+  sudo: True
+  gather_facts: True
+  vars:
+    serial_count: 1
+  serial: "{{ serial_count }}"
+  roles:
+    - common_vars
+    - docker
+    - rabbitmq