Distinguish route-to-cataloging exception circ messages

Distinguish route-to-cataloging exception circ messages

It appears as though a copy-and-paste error introduced duplicate keys in
circ.properties, which in turn makes newer versions of the Translate
Toolkit unhappy and results in empty translated files. Tracing through
the pertinent code in xul/staff_client/server/circ/util.js, it looks
like the desired key was for "not_found" for the second "cataloging" key
- so change that accordingly.

Signed-off-by: Dan Scott <dan@coffeecode.net>