Use docker-maven-plugin for building Docker images

[php-coder]

After porting to Spring Boot (#75) consider using docker-maven-plugin for building Docker images.

Related links:

• http://spring.io/guides/gs/spring-boot-docker/
• https://github.com/spotify/docker-maven-plugin
• https://github.com/rhuss/shootout-docker-maven
• https://github.com/alexec/docker-maven-plugin