Fix bug, flat model proxy should not do any data change notification for accounts, just for contacts. This change improves performance.
Fix bug, flat model proxy should not do any data change notification for accounts, just for contacts. This change improves performance.

freedesktop-unofficial-mirror/telepathy__telepathy-qt4-yell,freedesktop-unofficial-mirror/telepathy__telepathy-qt4-yell,freedesktop-unofficial-mirror/telepathy__telepathy-qt4-yell,freedesktop-unofficial-mirror/telepathy__telepathy-qt4-yell