Add indicators; Remove junk tags

First, we were not supplying authority tag indicators when generating the
overlay template.  The xml merge function does not currently transfer
indicators, but we need to do this anyway because newer MARC::Field version
balk at fields with no indicators.

Second, PG 9.1+ adds wrapper tags to xml content that is passed to XMLELEMENT
as an array.  So, we'll use XMLAGG to get around that.

Signed-off-by: Mike Rylander <mrylander@gmail.com>
Signed-off-by: Dan Wells <dbw2@calvin.edu>
Stamping 0847: improved auth overlay generation

Signed-off-by: Dan Wells <dbw2@calvin.edu>