Code review comment for lp:~artmello/camera-app/camera-app-multi_selection

I found a few problems with this MR in testing:

1) Long pressing an image causes the Share/Delete menu to be briefly shown then hidden
2) Select two images, then tap on a third one to view it. When you return to selection mode the previous selections are no longer selected as they should be. Then you can only single select from that point.
3) There should be a "select all" toggle button on the toolbar that toggles select all/select none. See address-book-app. This should perform the same way.
4) I found it's too easy to accidentally tap the photo to open it when I was trying to check the selection button. Maybe leave the visual size of the selection box the same but make a bigger touch area around such that we can increase the hit size without having to make the box bigger visually.