IS-08 test 5 incorrectly handles 204 responses
Due to an earlier change. The 'string' parameter no longer exists, so a 204 code with an empty body is attempted to be parsed as JSON.

https://github.com/AMWA-TV/nmos-testing/blob/master/is08/activation.py#L97
diff --git a/nmostesting/suites/is08/calls.py b/nmostesting/suites/is08/calls.py
index 9efa195..782c46d 100644
--- a/nmostesting/suites/is08/calls.py
+++ b/nmostesting/suites/is08/calls.py
@@ -52,7 +52,10 @@ class Call:
         self._checkForErrors()
         self._checkStatusCode()
         self._checkResponseSchema()
-        return self._getJSON()
+        if self.expectedCode != 204:
+            return self._getJSON()
+        else:
+            return None
 
     def _checkForErrors(self):
         if not self._callSucceeded:
['nmostesting/suites/is08/calls.py']