Fixed onos-app tool to exit with proper status.

Change-Id: Id3d4e703a2bf6f12208aeabb2cdaad87ca0c33af
diff --git a/tools/dev/bin/onos-app b/tools/dev/bin/onos-app
index 658a050..d6fe562 100755
--- a/tools/dev/bin/onos-app
+++ b/tools/dev/bin/onos-app
@@ -66,4 +66,7 @@
     *) usage;;
 esac
 
+
+status=$?
 echo # new line for prompt
+exit $status