LP#1287370: allow AutoGrid to persist filter state and page offset

LP#1287370: allow AutoGrid to persist filter state and page offset

By turning on a new AutoGrid option called urlNavigation,
the current filter and offset is stored in a URL parameter
called djgridops. This permits using the back button
to return to an AutoGrid page at the place in the search
results where the user left it.

Signed-off-by: Bill Erickson <berick@esilibrary.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>
Signed-off-by: Erica Rohlfs <erohlfs@esilibrary.com>
Signed-off-by: Mike Rylander <mrylander@gmail.com>
Signed-off-by: Ben Shum <bshum@biblio.org>