- Added patch-related methods to the ConverterService:
         applyPatch(Representation original, Representation patch) : Representation
         revertPatch(Representation modified, Representation patch) : Representation
         createPatch(Representation original, Representation modified) : Representation
       - Added patch(..) methods to ClientResource. Suggested by Brian Sletten.
       - Added patch(..) to ServerResource relying by default on the
         ConverterService and on the put(..) methods. Suggested by Brian Sletten.
       - Added IOException declaration to all the ConverterService methods.