FEAT: Slimline and templated Dockerfile

[carlwilson]

• moved to an all Alpine stack for build and the final image;
• now two Dockerfiles:
  • Dockerfile builds a tag by cloning the GitHub repo;
  • Dockerfile_dev builds a copy of the local project;
• added templated versions of both the above that are so that they are updated automatically as part of the Maven build; and
• updated the main pom.xml with a resource plugin to copy the Dockerfile and Dockerfile_dev to the base directory.