refactor(dockerfile) major rework

- based on openjdk:11-jre-slim instead of a base system and
    installing java manually
- removed git installation, we use a maven library for this
    no system installed git needed for anything
- removed this damn proxy env vars
    they have nothing to do baked into an docker image!!
- removed junit downloads
    not needed in backend. The testrunners are responsible
    for what they need
- removed setting of a specific profile
    in prod always the default one should be active,
    use a different profile on your dev machine which you
    DO NOT commit

Dockerfile

 #Dockerfile
 
 #base image
-FROM alpine
+FROM openjdk:11-jre-slim
 
-#Proxy
-ENV http_proxy 'http://proxy.hft-stuttgart.de:80'
-ENV https_proxy 'http://proxy.hft-stuttgart.de:80'
-
-
-#jdk11
-RUN apk add openjdk11 git
-
-VOLUME /tmp
-ADD target/modocot-backend-1.0.2-SNAPSHOT.jar app.jar
-RUN sh -c 'touch /app.jar'
+ADD target/modocot-backend.jar app.jar
 
 # Prepare environment.
 # Create needed folders
-RUN mkdir /home/modocot && \
-    mkdir /home/modocot/libs
+RUN mkdir /modocot && \
+    mkdir /modocot/data && \
+    mkdir /modocot/config
+
+VOLUME /modocot/data
 
-# Download needed libs for compilation
-ADD https://repo1.maven.org/maven2/junit/junit/4.13/junit-4.13.jar /home/modocot/libs/junit.jar
-ADD https://repo1.maven.org/maven2/org/hamcrest/hamcrest-core/2.2/hamcrest-core-2.2.jar /home/modocot/libs/hamcrest.jar
+env SPRING_CONFIG_ADDITIONAL_LOCATION "file:/home/modocot/config/"
 
-ENTRYPOINT ["java","-Djava.security.egd=file:/dev/./urandom","-Dspring.profiles.active=server","-jar","/app.jar"]
+ENTRYPOINT ["java","-Djava.security.egd=file:/dev/./urandom","-jar","/app.jar"]