Use a consistent spelling of "Pickup" throughout the code

LP#1155494 In myopac/holds.tt2 the text "PickUp Location" is
used, and everywhere else it's "Pickup Location".
Pick one spelling and stick to it.

Signed-off-by: Michael Peters <mpeters@emeralddata.net>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>