Vastly overhaul admin UI

Admin UI now has the ability to edit links that exist. Deleting items is
more accessible and asks for a confirmation before deleting. Link and
Category names as well as link descriptions now have a length limit
(todo: make it configurable?). Small bug fixes related to image saving
are also included in this commit.

zqdgr.config.json

@@ -13,6 +13,6 @@
         "dev": "go generate ./src/; PASSPORT_DEV_MODE=true go run src/main.go",
         "build": "go generate ./src/ && go build -tags netgo,prod -ldflags=\"-w -s\" -o passport"
     },
-    "pattern": "src/**/*.{go,hbs,css,svg,png,jpg,jpeg,webp,woff2,ico,webp}",
+    "pattern": "src/**/*.{go,hbs,scss,svg,png,jpg,jpeg,webp,woff2,ico,webp}",
     "shutdown_signal": "SIGINT"
 }