Trap 404s and return Rest_Exception instead. Fixes ticket #1213.

modules/rest/controllers/rest.php

@@ -87,6 +87,8 @@ public function __call($function, $args) {
       // either need to map the result values to localized strings in the application code, or every
       // client needs its own l10n string set.
       throw new Rest_Exception("Bad Request", 400, $e->validation->errors());
+    } catch (Kohana_404_Exception $e) {
+      throw new Rest_Exception("Not Found", 404);
     }
   }
 }