Metacat

Currently, the metacat servlet accepts documents that are not valid according to
their type. We need to change this behavior so that these documents are
rejected fromthe server. The only way to save a document that is invalid is to
remove the DOCTYPE assertion that the document is of a certain type. Thus, we
can save only "typeless" documents (with no Public ID) and "typed" documents
that are valid according to the DTD referenced by their Public ID.

This change will make metadata more predictable and therefore applications that
depend on metadata contents more reliable. It will require changes to the
various clients (web, java) to deal with the newly rejected documents.