Add Fullscreen in viewer, Track links with Google Analytics, Use .env file

- Fullscreen is a component that watches a store value set by the Carousel component on a picture click
- Use a .env file for API and website related settings and informations
- Google Analytics is now in place, tracking each routes link and viewer photo change

src/style/style.scss

@@ -31,6 +31,7 @@
 // Organisms
 @import "organisms/carousel";
 @import "organisms/photos";
+@import "organisms/fullscreen";
 @import "organisms/locations";
 @import "organisms/pagination";
 @import "organisms/footer";