Format payload as string in unauthenticated mode
Format payload as string in unauthenticated mode

per1234/TCPEvents/34b13bbb55877d05ec75ebdc550016c2a4c089ca causes
TCPEvents to assume TCPEvents clientType which cases the server to
attempt to evaluate payloads as python expressions. This EtherEvent
commit formats the sent payload as a string so that TCPEvents won't
attempt to evaluate it as python.

per1234/EtherEvent