LP#1736269: Mark Missing Pieces is non-functional

LP#1736269: Mark Missing Pieces is non-functional

In the work to separate the item service into a reusable component, a
reference to $scope was left hanging around.  This causes the service to die
before it can complete its work.  The code using $scope does seem to be
necessary, so we'll have the function accept an outer_scope parameter and
adjust the call sites.

Signed-off-by: Mike Rylander <mrylander@gmail.com>
Signed-off-by: Cesar Velez <cesar.velez@equinoxinitiative.org>
Signed-off-by: Chris Sharp <csharp@georgialibraries.org>