Install packages in docker container to enable flask profiling (#351)

* add packages to docker container for profiling

* make things less restrictive

* repin due to build error

docker/Dockerfile

@@ -25,6 +25,8 @@ RUN pip install --no-cache-dir --upgrade pip \
         pymysql>=1.0.0 \
         psycopg2-binary \
         gunicorn \
+        werkzeug==0.16.0 \
+        markupsafe==2.0.1 \
     && rm -rf /terracotta
 
 COPY docker/resources /