Added tests for updateResponseForLiteralData() method of OutputDataItem.java

This class is for testing the updateResponseForLiteralData() method of
the class OutputDataItem.java. You will see that while creating each of
the currently supported LiteralDataBinding-outputs the message: "[Fatal
Error] :1:1: Content is not allowed in prolog." is logged. This happens
because it is tried to parse the literal data values as XMLObjects. Do
you see situations, in which the parsing actually makes sense? XML in
literal string outputs perhaps? Otherwise, I would have a fix
ready, which would be my next pull request.