Metacat

After finishing the replication feature of metacat, the xml_replication table
was added some new fields such as datafilereplicate and hub.

xmltables.sql and xmltables_postgres were revised. But they only are used for
create a new database. If we apply them in our production version of metacat,
we will lose our all metacat data!

So we need a new script file which only replace the xml_replication tables
itself and keep other tables same. Maybe serverid in xml_replication tables is
a foreign key of xml_documents table is a issue need to be figured out.