Dataproxy should not default to utf8

[ross]

Unless explicitly told by the source web server the dataproxy should not assume that the content it has can be encoded as UTF-8. Even though the chars from 128 - 255 overlap an attempt to decode some byte array as utf8 will fail whenever a latin1 char whose bitpattern has the MSB set.

This will mean that the UTF8Recoder can be more rigid in its acceptance of data, Postel aside.

[ross]

Have pushed back to 1.9 but if may be the the converter service will replace it in the meantime.