Updated some comment elements and standardised more JS

- Updated comment routes to be simpler.
- Updated comments JS to align better with updated component system.
- Documented available global JS functions/services.
- Removed redundant controller method.
- Added window.$events helpers for validation messages and
success/error.
- Updated JS events system to not be class based for simplicity.
- Added window.trans_plural method to handle pluralisation/replacements
where you already have the translation string itself.

Fixes #1836

app/Http/Controllers/Controller.php

@@ -8,6 +8,7 @@ use Illuminate\Foundation\Validation\ValidatesRequests;
 use Illuminate\Http\Exceptions\HttpResponseException;
 use Illuminate\Http\Request;
 use Illuminate\Routing\Controller as BaseController;
+use Illuminate\Validation\ValidationException;
 
 abstract class Controller extends BaseController
 {
@@ -132,23 +133,6 @@ abstract class Controller extends BaseController
         return response()->json(['message' => $messageText, 'status' => 'error'], $statusCode);
     }
 
-    /**
-     * Create the response for when a request fails validation.
-     * @param  \Illuminate\Http\Request  $request
-     * @param  array  $errors
-     * @return \Symfony\Component\HttpFoundation\Response
-     */
-    protected function buildFailedValidationResponse(Request $request, array $errors)
-    {
-        if ($request->expectsJson()) {
-            return response()->json(['validation' => $errors], 422);
-        }
-
-        return redirect()->to($this->getRedirectUrl())
-            ->withInput($request->input())
-            ->withErrors($errors, $this->errorBag());
-    }
-
     /**
      * Create a response that forces a download in the browser.
      * @param string $content