Reduce view add/removes when loading photos

Reduce view add/removes when loading photos

Two fixes to reduce flicker when loading images. First, adjust
ViewItem instances in-place instead of creating new ViewItems
which included adding and removing views from the hierarchy.
It turned out we were doing an update for every photo due to
touching PanoramaMetadata and reporting back that metadata
was adjusted, whether or not a photo was a panorama. Now
that data is reported. New photo captures are essentially
added and removed from the view hierarchy three times before
this change, after an ImageView is added once, with its
contents changed as the photo is loaded.

More testing is needed but I cannot repro the elusive filmstrip
flicker with these changes.

Bug: 18977838
Bug: 17905863
Change-Id: I5a42c0baf87a8cef0ee4dbcf9f03d40715e6aa2d