Update to cope with current WPS developmenrts

The encoding "UTF-8" doesn't have to be specified no more, because it is
the default encoding.
Added logger, adjustments to current WPS

The following doesn't seem to work anymore:
processOutput.getData().getComplexData().newInputStream();
It returns the content of the complexdata element wrapped in a
<xml-fragment> element. Accessing the first child of the Dom node
returns the content only. There is also a method
getComplexValueNodeString in InputHandler which does the same thing but
different. If this is the way to go, this should probably be moved to
XMLUtils in the commons module.