show Updating progress notification based on "available updates" pref

The notification that shows the download/parse progress of the index update
is now controled by the "Show available updates" preference.  That means it
will not be shown at all in the notifications bar if that preference is
disabled.  There will still be the header inside of F-Droid.  Ideally, the
Updating process would be shown in the Updates tab.

app/src/main/java/org/fdroid/fdroid/UpdateService.java

@@ -319,14 +319,14 @@ public class UpdateService extends JobIntentService {
                     } else {
                         notificationBuilder.setProgress(100, 0, true);
                     }
-                    notificationManager.notify(NOTIFY_ID_UPDATING, notificationBuilder.build());
+                    setNotification();
                     break;
                 case STATUS_ERROR_GLOBAL:
                     text = context.getString(R.string.global_error_updating_repos, message);
                     notificationBuilder.setContentText(text)
                             .setCategory(NotificationCompat.CATEGORY_ERROR)
                             .setSmallIcon(android.R.drawable.ic_dialog_alert);
-                    notificationManager.notify(NOTIFY_ID_UPDATING, notificationBuilder.build());
+                    setNotification();
                     Toast.makeText(context, text, Toast.LENGTH_LONG).show();
                     break;
                 case STATUS_ERROR_LOCAL:
@@ -344,7 +344,7 @@ public class UpdateService extends JobIntentService {
                     notificationBuilder.setContentText(text)
                             .setCategory(NotificationCompat.CATEGORY_ERROR)
                             .setSmallIcon(android.R.drawable.ic_dialog_info);
-                    notificationManager.notify(NOTIFY_ID_UPDATING, notificationBuilder.build());
+                    setNotification();
                     Toast.makeText(context, text, Toast.LENGTH_LONG).show();
                     break;
                 case STATUS_COMPLETE_WITH_CHANGES:
@@ -353,12 +353,18 @@ public class UpdateService extends JobIntentService {
                     text = context.getString(R.string.repos_unchanged);
                     notificationBuilder.setContentText(text)
                             .setCategory(NotificationCompat.CATEGORY_SERVICE);
-                    notificationManager.notify(NOTIFY_ID_UPDATING, notificationBuilder.build());
+                    setNotification();
                     break;
             }
         }
     };
 
+    private void setNotification() {
+        if (Preferences.get().isUpdateNotificationEnabled()) {
+            notificationManager.notify(NOTIFY_ID_UPDATING, notificationBuilder.build());
+        }
+    }
+
     /**
      * In order to send a {@link Toast} from a {@link IntentService}, we have to do these tricks.
      */
@@ -404,7 +410,7 @@ public class UpdateService extends JobIntentService {
             }
 
             updating = true;
-            notificationManager.notify(NOTIFY_ID_UPDATING, notificationBuilder.build());
+            setNotification();
             LocalBroadcastManager.getInstance(this).registerReceiver(updateStatusReceiver,
                     new IntentFilter(LOCAL_ACTION_STATUS));