avoid exceptions when updating jobs if "message" is not a string

WIP on #205

ippisite/ippidb/models.py

@@ -1721,13 +1721,13 @@ class Job(models.Model):
         if output == "std_out":
             print(message, file=sys.stdout)
             split_std_out = self.std_out.split("\n")
-            split_std_out = split_std_out + message.split("\n")
+            split_std_out = split_std_out + str(message).split("\n")
             self.std_out = "\n".join(split_std_out[-100:])
             self.save()
         elif output == "std_err":
             print(message, file=sys.stderr)
             split_std_err = self.std_err.split("\n")
-            split_std_err = split_std_err + message.split("\n")
+            split_std_err = split_std_err + str(message).split("\n")
             self.std_err = "\n".join(split_std_err[-100:])
             self.save()
         else: