Add Dockerfile and rough container file structure

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)

Dockerfile

@@ -0,0 +1,12 @@
+FROM		alpine:edge
+MAINTAINER	Jona Reichmann
+
+RUN	apk update \
+	&& apk upgrade \
+	&& apk add \
+		curl
+		jq
+
+ADD fsRoot /
+
+CMD ["bash", "-c", "/opt/minecraft/entrypoint.sh"]

fsRoot/opt/minecraft/downloadServer.sh

@@ -0,0 +1,19 @@
+#!/bin/bash
+
+BASE_DOWNLOAD_URL="https://s3.amazonaws.com/Minecraft.Download/versions/"
+VERSION_INFO_URL="https://launchermeta.mojang.com/mc/game/version_manifast.json"
+
+function query_latest_release() {
+	curl -s "$VERSION_INFO_URL" | jq -r '.latest.release'
+}
+
+function query_latest_snapshot() {
+	curl -s "$VERSION_INFO_URL" | jq -r '.latest.snapshot'
+}
+
+function download_version() {
+	local version="$1"
+	local url="${BASE_DOWNLOAD_URL}${version}/minecraft_server.${version}.jar"
+	curl -s -o "minecraft_server.jar" $url
+}
+