sync debug log just if data receivces

src/de/tudarmstadt/informatik/hostage/sync/Synchronizer.java

@@ -121,7 +121,8 @@ public class Synchronizer {
             ArrayList<SyncDevice> otherDevices = new ArrayList<SyncDevice>();
             ArrayList<String> ownDevicesds = this.dbh.getAllDevicesIds();
 
-            Log.i("DEBUG_Sync", "Updating Devices: " + otherDevices.size());
+            if (otherDeviceIds.size() > 0)
+                Log.i("DEBUG_Sync", "Updating Devices: " + otherDevices.size());
 
             ArrayList<String> n = this.diffArray(otherDeviceIds, ownDevicesds);
             for (String deviceId : n){