Added support for fat jars

Hi @jstrachan,

I've just added a basic run script the image, so we can distinguish between `MAIN` classes, and fat `JAR`s. With current version of the image I can't properly execute fat jars.

With my change we can configure jar to be executed:

    <env>
      <JAR>${project.artifactId}-${project.version}.jar</JAR>
    </env>

Instead of the main class:
          
    <env>
      <MAIN>io.fabric8.quickstarts.java.simple.Main</MAIN>
    </env>

BTW I see that Roland uses `jolokia` namespace for his images [1], instead of `consol`.

Cheers.

[1] https://github.com/rhuss/docker-java-jolokia