relaxed constraints for detecting privileged container

Branch: rokane8/per-build-container:feature/docker-privileged-path
Branch: atlassian/per-build-container:master
Merged
Merged pull request
Merged in rokane8/per-build-container/feature/docker-privileged-path (pull request #208)
Description
We're currently using a docker registry mirror to host all of our images. This PR relaxes the requirements for detecting a "dind" image and enabling the privileged flag.
Once we mirror the image in our docker registry it is generally of the format "project/image:tag". Eg: bamboo-pbc/docker:18.03-dind