Revert "Update FontAwesome package"

This reverts commit 0eeb0715.

package.json

@@ -11,7 +11,7 @@
   "dependencies": {
     "clipboard": "^2.0.4",
     "es6-shim": "^0.35.5",
-    "@fortawesome/fontawesome-free": "^5.122.0",
+    "font-awesome": "^4.7.0",
     "highlight.js": "^9.16.2",
     "jquery": "^3.4.1",
     "jquery-ui": "^1.12.1",