Block "Place Hold" link in TPAC if item is available

Block "Place Hold" link in TPAC if item is available

Suppress the display of the "Place Hold" link based on whether an item
is available. This is set as a preference in config.tt2. Some sites
may want the ability to place holds regardless of availability.

Signed-off-by: Art Rhyno <art632000@yahoo.ca>
Signed-off-by: Dan Scott <dscott@laurentian.ca>
Conflicts:
	Open-ILS/src/templates/opac/parts/record/summary.tt2
	Open-ILS/src/templates/opac/parts/result/table.tt2

Signed-off-by: Dan Scott <dscott@laurentian.ca>