Add Binder configuration (currently untested)

binder/apt.txt

+default-jre-headless

binder/postBuild

+#!/bin/bash
+
+set -o errexit
+set -o nounset
+set -o pipefail
+set -o verbose
+
+PROB2_JUPYTER_VERSION="1.1.0"
+JAR_NAME="prob2-jupyter-kernel-${PROB2_JUPYTER_VERSION}-all.jar"
+
+wget "https://www3.hhu.de/stups/downloads/prob2-jupyter/${JAR_NAME}"
+java -jar "${JAR_NAME}" install --user
+# Remove no longer needed files to reduce size of image.
+rm "${JAR_NAME}"