from python2 to python3 > ok from command line

src/jflow/server.py

@@ -161,9 +161,10 @@ class JFlowServer (object):
             value = func(*args, **kw)
             cherrypy.response.headers["Content-Type"] = "application/json"
             # if JSONP request
-            if "callback" in kw: return kw["callback"] + "(" + json.dumps(value, cls=JFlowJSONEncoder) + ")"
+            if "callback" in kw: 
+                return ('%s(%s)' % (kw["callback"], json.dumps(value, cls=JFlowJSONEncoder))).encode('utf8')
             # else return the JSON
-            else: return json.dumps(value)
+            else: return json.dumps(value, cls=JFlowJSONEncoder).encode('utf8')
         return wrapper
 
     def jsonify_workflow_status(self, workflow, init_to_zero=False):