Gallery:Fix page skipping error after the editing

1. Add isLoading function at ClusterAlbumSet and ClusterAlbum.
2. Add isLoading function at FilterDeleteSet.
3. Modify ReloadTask in PhotoDataAdapter to control the loop by
   using the isLoading function.

Change-Id: If3578294163120a0b52db0696deb7d5a764e0c1c
CRs-Fixed: 1042817