Downgrade to pydot-1.0.2 to fix unknown graph rendering error

requirements.txt

@@ -12,6 +12,6 @@ paramiko==2.0.0
 psycopg2==2.6.1
 py-gfm==0.1.3
 pycrypto==2.6.1
-pydot==1.1.0
+pydot==1.0.2
 sqlparse==0.1.19
 xmltodict==0.10.2