LP 1160522 2.3 tpac search modifier query append

Append search modifiers (e.g. limit to available) to the end of the
tpac search query to avoid SQL generation issues with 2.3 series
query parser.

Signed-off-by: Bill Erickson <berick@esilibrary.com>
Signed-off-by: Ben Shum <bshum@biblio.org>