Create a docker image for OpenMRS webapp

1) Create a docker image for the OpenMRS web app.
2) Publish the docker image to Docker Hub registry. *
3) Write a document explaining the implementation details and how-tos on OpenMRS wiki.*

See more about docker at: https://docs.docker.com/terms/image/
Related ticket: https://issues.openmrs.org/browse/TRUNK-4376
*Publish links here as a comment.