Added @throws TokenMismatchException

Since modern IDE's will expect you to define the @throws attribute, added this to the Docblock.

app/Http/Middleware/CsrfMiddleware.php

@@ -11,6 +11,7 @@ class CsrfMiddleware implements Middleware {
 	 *
 	 * @param  \Illuminate\Http\Request  $request
 	 * @param  \Closure  $next
+	 * @throws TokenMismatchException
 	 * @return mixed
 	 */
 	public function handle($request, Closure $next)