Added openjdk8-jre from the default alpine repos, set JAVA_HOME and PATH env variables accordingly.
Also fixed deprecated Dockerfile syntax: `MAINTAINER` -> `LABEL maintainer="..."`
Added Dockerfile based on alpine:edge with the following packages:
- curl - for downloading the server & querying for versions
- jq - parsing JSON from bash
Set up internal file structure of the container with scripts to download and run the server (unfinished)