Drop gunicorn and bind to 0.0.0.0 (#12)

Reviewed-on: #12
Co-authored-by: Madis Mägi <madis.magi@k-space.ee>
Co-committed-by: Madis Mägi <madis.magi@k-space.ee>

doorboy.py

@@ -59,4 +59,4 @@ async def view_longpoll(request):
     return stream(g, content_type="text/event-stream")
 
 if __name__ == '__main__':
-    app.run(debug=False, port=5000)
+    app.run(debug=False, host='0.0.0.0', port=5000)