BFD: add ARP-awareness, fix bugs

Make BFD ARP-aware when sending out packets.
Fix a few one-liner bugs discovered while integrating with cisco
nexus. Enhance CLI view to better observe session state.

Change-Id: I266c29492f351207b84328ab665d9d697969da9c
Signed-off-by: Klement Sekera <ksekera@cisco.com>
diff --git a/src/vnet/bfd/bfd_main.h b/src/vnet/bfd/bfd_main.h
index 4d460f4..d722a55 100644
--- a/src/vnet/bfd/bfd_main.h
+++ b/src/vnet/bfd/bfd_main.h
@@ -316,7 +316,8 @@
 			 bfd_session_t * bs);
 void bfd_event (bfd_main_t * bm, bfd_session_t * bs);
 void bfd_init_final_control_frame (vlib_main_t * vm, vlib_buffer_t * b,
-				   bfd_main_t * bm, bfd_session_t * bs);
+				   bfd_main_t * bm, bfd_session_t * bs,
+				   int is_local);
 u8 *format_bfd_session (u8 * s, va_list * args);
 u8 *format_bfd_auth_key (u8 * s, va_list * args);
 void bfd_session_set_flags (bfd_session_t * bs, u8 admin_up_down);