[Blasq] Derive PhotosProxyModel from NamedModel itself.
[Blasq] Added CollectionRoleMax.
[Blasq] Added ISupportDeletes interface.
[Blasq] Added & implemented SupportsDeletes custom role.
[Blasq] Delete button in PhotoView.
[Blasq] PhotosTab::ImageID2Index().
[Blasq] Handle Delete button.
[Blasq Rappor] Implement ISupportDeletes.
[Blasq] Added scale slider.
[Blasq] Store scale slider values.
[Blasq] Upgrade to medium thumb on big image size.