Calling Jolokia opts script

Hi @jstrachan,

As described here [1], Jolokia image comes with the `/bin/jolokia_opts` script. We should call this script before invoking Java process:

    export JAVA_OPTIONS="$JAVA_OPTIONS $(jolokia_opts)" 

With this change we can take advantage of Jolokia `ENV` options like `JOLOKIA_OFF`:

    docker run -e JOLOKIA_OFF -it 6c45e8fa2a04

I changed our image to call `jolokia_opts` instead of setting fixed `JAVA_OPTIONS`.

Cheers.

[1] https://registry.hub.docker.com/u/jolokia/java-jolokia/