Stop Gadgetbridge from ignoring initial message.

Gadgetbridge seems to ignore the first line sent to it after connecting.
This commit works around this by prepending each message with a blank line.

apps/gbridge/widget.js

@@ -13,6 +13,7 @@
   };
 
   function gbSend(message) {
+    Bluetooth.println("");
     Bluetooth.println(JSON.stringify(message));
   }