Added Dockerized support

[WernerRaath]

To make it easier for myself, since I do not have maven etc. installed on my machine, I have created a easy to run Docker for this repo. Thus making it easy to run the grib2json utility without all the dependencies installed on my machine.

I do how-ever get errors on my machine in running the grib2json util, even with the dependencies installed on my machine. Would like some input regarding why the exception is thrown.

[claustres]

This fork might help: https://github.com/weacast/weacast-grib2json.