Fix converting binary SOAP Request & Reply data to strings.
Request & Reply 'message' member contains binary & not unicode-string data. When a string is needed (e.g. when logging SOAP request or reply content) we now use Python's internal and non-ambiguous representation for this data.
Optionally, we could 'assume the data is actually an utf-8 encoded unicode string', decode it and get a bit nicer string output, i.e. without the "b''" wrapper and without having non-ASCII characters displayed as escaped hexadecimal character codes, but that would require much more detailed usage research to make sure our assumption holds.