Photo: Code optimization

- Avoid double declaration of sources
- Use class over an HTML tag for image reveal animation

src/animations/Photo.js

@@ -28,7 +28,7 @@ export const animateIn = scope => {
     // Photo appearing
     const photoReveal = ScrollOut({
         once: true,
-        targets: scope.querySelector('picture'),
+        targets: scope.querySelector('.photo__image'),
         onShown (el) {
             // Load the photo then reveal it
             imagesLoaded(el, instance => {