bug 2677: restore RandomizeHoldsQueueWeight and StaticHoldsQueueWeight

bug 2677: restore RandomizeHoldsQueueWeight and StaticHoldsQueueWeight

Restoring the functionality of these sysprefs as part of the
rework of build_holds_queue.pl:

* StaticHoldsQueueWeight is an ordered list of library codes.
  The order of the libraries in this list determines the order
  of libraries in which available items will be chosen to be
  targeted to holds.  Note that if this list does not include
  a library, items from that library will never be targeted to
  holds and staff will never be asked to retrieve items for
  title-level holds from those libraries.

* RandomizeHoldsQueueWeight is a Boolean parameter, indicating
  whether to randomize the libraries in the StaticHoldsQueueWeight
  list.

If neither RandomizeHoldsQueueWeight nor StaticHoldsQueueWeight is
set, then the libraries will be used to target items to holds in
alphabetical order by library code.

Signed-off-by: Galen Charlton <galen.charlton@liblime.com>