Use doxec version 0.2.0

Update the docker image to use doxec version 0.2.0 with improved user interface.

Dockerfile

@@ -10,6 +10,6 @@ RUN apt-get update && apt-get install -y  \
   && rm -rf /var/lib/apt/lists/*
 
 # install doxec
-RUN git clone https://srv.sauerburger.com/esel/doxec.git && cd doxec && git checkout b0ce804f && python3 setup.py install 
+RUN git clone https://srv.sauerburger.com/frank/doxec.git && cd doxec && git checkout v0.2.0 && python3 setup.py install 
 RUN echo "" | adduser --disabled-password student && echo "student ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers
 USER student