Backport r15336 from trunk: Give sites the ability to easily display due dates and...

Backport r15336 from trunk: 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/branches/rel_1_6@15337 dcc99617-32d9-48b4-a31d-7c20da2025e4