Put remote boot UUID in ServerStatistics and RemoteMessage

This makes it so we can see when a remote reboots easily, and gives us a
stepping stone to putting it in the log file header.

RemoteMessage then goes to the logger, so we are ready to teach the
logger how to detect and handle reboots.

Change-Id: I943de46094b60535c92a677b430d6828933b820d
diff --git a/aos/network/connect.fbs b/aos/network/connect.fbs
index b593472..7ff2fbe 100644
--- a/aos/network/connect.fbs
+++ b/aos/network/connect.fbs
@@ -10,4 +10,9 @@
 
   // The channels that we want transfered to this client.
   channels_to_transfer:[Channel] (id: 1);
+
+  // The UUID that this node booted with.
+  boot_uuid: string (id: 2);
 }
+
+root_type Connect;