Support for secured SOAP attachments

The attached patches should serve as a basis for discussions how
the support for SwA in WSS4j and the integration in
a SOAP-Stack should look like.

Some notes to the patch:

• Applies to the current trunk of santuario and wss4j.
• The client side demonstrates the DOM approach whereas the server side uses the StAX implementation.
• I've implemented the very basic just to have a working proof-of-concept.
• Attachments are requested via callback from the soap-stack because
• of decoupling from soap-stack
• to support full streaming from network to SIB as far as possible

• CXF dependencies are just a leftover from V1 and because the SecurityInInterceptor is not ported to V2
• Encryption / Decryption of an attachment is streaming oriented, no buffering is done in WSS4J.
• Signature creation and verification is at the moment buffered in WSS4j but the signature-verification can, under some conditions, be streamed as well.
• To prevent patching of CXF for the prototype the WSS4J Interceptors and some dependencies are copied and modified and also included in the patch. The santuatio changes are necessary for the StAX impl.
  For DOM all necessary santuario changes are done via reflection or other hacks for now.

Feedback is very welcome and also necessary!

Thanks,

Marc