Adds example project using jib-maven-plugin.

[coollog]

Fixes #61

This project builds a simple HelloWorld application that uses one resource file and one dependency.

[coollog]

@mattmoor This may be handy as an example to play around with.

[elharo]

For examples like this it's good if we can keep dependencies to an absolute minimum, not even Guava.

[coollog]

This example was intended to show how Jib can pack dependencies, resources, and classes into separate layers and that running the final image runs the application accordingly. I included Guava as an example dependency. Should I remove it and leave it as just a class and a resource instead?