Exclude some problematic transitive dependencies

The xml-apis API is (AFAICT) already bundled with
J2SE, so there is no need to depend on it explicitly.

The xalan and serializer projects provide an XML
implementation for the interfaces in core J2SE.

Sure, depending on these components might be better
for performance and/or correctness (i.e., less buggy
than core J2SE's bundled implementation).

Unfortunately, these libraries also wreak havoc with
Maven dependency resolution downstream.

For some related information, see:
http://stackoverflow.com/q/11677572