Dockerfile: fix home dir for app user (/home/app)

Dockerfile

@@ -7,9 +7,9 @@ RUN pip install --no-cache-dir -r requirements.txt gunicorn
 
 COPY . .
 
-RUN addgroup --system --gid 1000 app && adduser --system --uid 1000 --ingroup app app && \
+RUN addgroup --system --gid 1000 app && adduser --system --uid 1000 --ingroup app --home /home/app app && \
+    mkdir -p /home/app && chown app:app /home/app && \
     chown -R app:app /app && chmod -R u+w /app
-ENV HOME=/app
 USER app
 
 EXPOSE 5005