Created protocol property in QDeclarativeContactOnlineAccount.

Exported protocol property and OnlineAccountProtocol enum in QDeclarativeContactOnlineAccount.

Task-number: QTBUG-32142

Change-Id: I4e3a5fda659bbb48b56e83b96de3e59a03549c31
Reviewed-by: Christopher Adams <chris.adams@jollamobile.com>
Reviewed-by: Alex <alexander.blasche@digia.com>
Prevent duplicated contacts on QDeclarativeContactModel.

Fixed contact update function to use 'dataChanged' signal insted of 'beginInsertRows' which causes contact duplication.

Task-number: QTBUG-32324
Change-Id: Ic872da1caa9db6faf6f3f1be3fc78df448d92baf
Reviewed-by: Christopher Adams <chris.adams@jollamobile.com>
Reviewed-by: Robin Burchell <robin+qt@viroteck.net>