openflow_input: add BSN extensions to OF 1.4

I left out the following extensions that are no longer used or have been
superceded by the standard:

 - bsn_disable_split_horizon_check
 - bsn_role_status
 - bsn_global_vrf_allowed
diff --git a/openflow_input/bsn_flow_idle b/openflow_input/bsn_flow_idle
index 40a95d8..e0139e2 100644
--- a/openflow_input/bsn_flow_idle
+++ b/openflow_input/bsn_flow_idle
@@ -29,6 +29,7 @@
 // governing permissions and limitations under the EPL.
 
 #version 4
+#version 5
 
 /*
  * Notification of idle flows