Lp 1694058: Fix Issue With Place Holds Reported in Testing

Lp 1694058: Fix Issue With Place Holds Reported in Testing

When staff did have to override in order to place the hold, and the
"Place another hold for this title" link was subsequnetly used, the
inputs for the patron barcodes and some other fields on the place
holds page were duplicated.  To avoid this, we now use uniq from the
List::MoreUtils library when retrieving the hold targets list from the
CGI parameters.

Signed-off-by: Jason Stephenson <jason@sigio.com>
Signed-off-by: Kathy Lussier <klussier@masslnc.org>