Give sites the ability to easily display due dates and times in the OPAC under "copy...

Give sites the ability to easily display due dates and times in the OPAC under "copy details"

We add two new variables to copy_details.js:
  * showDueDate - this needs to be set to a non-false value to display the
    due date in the OPAC
  * showDueTime - this needs to be set to a non-false value to display the
    due time in the OPAC, along with the due date. If showDueDate is false,
    then the value of this variable is ignored.

git-svn-id: svn://svn.open-ils.org/ILS/trunk@15336 dcc99617-32d9-48b4-a31d-7c20da2025e4