Dev 0.11 (#175)

* use random IP adresses for unit tests

* Docker: The description ist missing (#171)

Fixes #167

* S allius/issue167 (#172)

* cleanup

* Sonar qube 6 (#174)

* test class ModbusConn

app/tests/test_singleton.py

@@ -7,6 +7,7 @@ class Test(metaclass=Singleton):
         pass  # is a dummy test class
 
 def test_singleton_metaclass():
+    Singleton._instances.clear()
     a = Test()
     assert 1 == len(Singleton._instances)
     b = Test()