Switch to next photo

[benfrancis]

As a user, when viewing a photo full screen, I want to switch to the next photo by swiping my finger so I can switch between full screen views of photos without navigating back to a collection of thumbnails

Acceptance Criteria

• When viewing a photo, can the user slide the next photo (from either direction) into view using their finger?
• If the next photo is more than 50% across the screen when the user releases their finger, does the next photo smoothly snap into view?
• If the next photo is less than 50% across the screen when the user releases their finger, does the current photo smoothly snap back into view?
• If the user tries to switch past the last photo, is a black background displayed, then the current photo smoothly snaps back into view when they release their finger?