Pebble: delay 100ms after writing a pebble packet to the output steam

This fixes a problem on newer firmwares, probably from 3.0 on, where sending an
appmessage packet right after acknowledging a previous incoming appmessage
packet results in our outgoing appmessage packet to be NACKed by the pebble
firmware and not even reaching the app running on the pebble.

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/pebble/PebbleIoThread.java

@@ -457,6 +457,10 @@ public class PebbleIoThread extends GBDeviceIoThread {
         } catch (IOException e) {
             LOG.error("Error writing.", e);
         }
+        try {
+            Thread.sleep(100);
+        } catch (InterruptedException ignored) {
+        }
     }
 
     @Override