Add support for container releases

Add support for container releases

- Add support for distribution_type container
- Add conditional build step.
If {build-node} is ^.*-docker-.*
docker login will occur for verify and merge.
- Trigger updated to support hidden releases
directory. (releases\/.*\.yaml|\.releases\/.*\.yaml)
- Container support:
    container_release_file example:

        containers:
            - name: example
            version: 1.5.1-20190806T184921Z

    - Verify pulls container
    - Grab the image_id
    - Merge
    - Apply tag
    - Push the container

ISSUE: RELENG-2292
Signed-off-by: Aric Gardner <agardner@linuxfoundation.org>
Change-Id: Ibc6cf1a22bd6c0136a94d2b434c6cd332c12b43f