Remove Dino WSDL tests and restructure io_fews

[OnnoEbbens]

The Dino WSDL api is down for almost two weeks now and I don't expect it to come up again. I removed the tests involving this api.

Other changes include:

• renaming io_xml to io_fews as it is specific for fews xml files
• restructure io_fews to avoid duplicate code
• add tests for io_fews