Optimize the static files

- Use webfont version of FontAwesome
- Use CDN for UIKit JS files

public/css/mango.less

@@ -1,3 +1,10 @@
+// UIKit
+@import "./uikit.less";
+
+// FontAwesome
+@import "../../node_modules/@fortawesome/fontawesome-free/less/fontawesome.less";
+@import "../../node_modules/@fortawesome/fontawesome-free/less/solid.less";
+
 // Item cards
 .item .uk-card {
     cursor: pointer;