LP#1738249: sort out circ or renewal workstation

LP#1738249: sort out circ or renewal workstation

This patch uses accs to work out the name of the workstation
of the most recent renewal, if it exists, or the original
checkout. It implicitly handles the case where the workstation
on the original circulation is null.  As a bonus, this patch
adds an explicit "Last Renewal Workstation" to the item status
grid.

Signed-off-by: Galen Charlton <gmc@equinoxinitiative.org>
Signed-off-by: Cesar Velez <cesar.velez@equinoxinitiative.org>
Signed-off-by: Jason Stephenson <jason@sigio.com>