feat: use gunicorn in dev mode

Author: sergiofenoll

start.sh

@@ -2,7 +2,7 @@
 set -eu
 if [ ${MODE:-""} == "development" ]; then 
     if [ -f /app/requirements.txt ]; then pip install -r /app/requirements.txt; fi
-    exec python web.py
+    exec gunicorn -k egg:meinheld#gunicorn_worker -c "$GUNICORN_CONF" "$APP_MODULE"
 else 
     exec gunicorn -k egg:meinheld#gunicorn_worker -c "$GUNICORN_CONF" "$APP_MODULE"
 fi