Proof-of-concept: Add shade mojo to create ueber jar

I know there is a good reason the support for an one/uber jar was dropped. But still, having such functionality can be quite handy. That's why I made this mojo to generate such a file using the maven-shade-plugin. Using its transformers, it is possible to avoid a lot of problems the one jar goal had before.

As the title states, this is a proof-of-concept and open for discussion.