Changed the way authority tags were being pulled to specifically use an aggregate...

Changed the way authority tags were being pulled to specifically use an aggregate array.

There appears to have been a change in postgres at some point between 9.0 and 9.1
to the aggregate method. Because of this, postgres was not returning the proper
results when pulling tags for authorities. This change will force postgres to do
a proper aggregate array call and return the correct results.

Signed-off-by: Steven Callender <stevecallender@esilibrary.com>
Signed-off-by: Bill Erickson <berick@esilibrary.com>