Dockerfile: Adding the npme server in a Docker container image.

This commit follows the steps to setup the npmE server in a
Docker container. It initially provides the steps to setup the
server with CENTOS 7, with a user "npme" without password.

*	new file:   Dockerfile
- Dockerfile that builds the server.

*	modified:   README.md
- Updated README with instructions of how it will run in the future.