Ignore WP2 tests for the time being (since they're being worked on).
Fix for whitespace handling when using Xerces parser.

 - Use a StringBuilder for concatenating the char buffer
 - Don't remove whitespace-only char strings because these become
   significant when they have a set of chars on one side and an
   XML entity (e.g. a quot) on the other
 - Normalise whitespace with StringUtils before its added to the
   graph.