fix tornado version to 5.1.1

Author: MadisKarli

Dockerfile

@@ -33,7 +33,7 @@ RUN apt-get update && apt-get install -y  \
     apt-get clean autoclean && \
     apt-get autoremove -y && \
     pip install ws4py==0.3.2 && \
-    pip install tornado && \    
+    pip install tornado==5.1.1 && \    
     ln -s /usr/bin/python2.7 /usr/bin/python ; ln -s -f bash /bin/sh
 
 WORKDIR /opt