#339 metadata xmlns:opendocument wrong if output type changed

[Terry O'Neill]

This bug is for the xena-named-output branch.

When an office file is output with a output conversion type other than Open Document Format chosen (note that this only applies to the office plugin as this is the only plugin which currently allows alteration of the output conversion type) then the metadata attribute of xmlns:opendocument on tag opendocument:opendocument is wrong. It is currently always "http://preservation.naa.gov.au/odf/1.0". Note that other metadata items in this tag are wrong as well but are covered by the following other bugs:

3378125 - Metadata for opendocument type ambiguous
3304429 - hardcoded Open Document Format in description