msobczyk/handle signals in docker entrypoint

handle signals in docker entrypoint, handle exit in start_clive script (close container on terminal close), closes issue #274 (closed)

docker/Dockerfile

@@ -25,7 +25,7 @@ ENV PATH="${PYTHON_VENV_PATH}/bin:$PATH" VIRTUAL_ENV=${PYTHON_VENV_PATH}
 
 RUN --mount=type=cache,mode=0777,sharing=locked,target=${APT_CACHE_DIR} \
     apt-get update && \
-    apt-get install -y sudo && \
+    apt-get install -y procps sudo && \
     apt-get clean && \
     rm -rf /var/lib/apt/lists/* && \
     useradd -d /clive -ms /bin/bash -u ${CLIVE_UID} -g users -c "clive application account" "clive" && \