updated elixir description in gulpfile from sass to less

gulpfile.js

@@ -6,7 +6,7 @@ var elixir = require('laravel-elixir');
  |--------------------------------------------------------------------------
  |
  | Elixir provides a clean, fluent API for defining some basic Gulp tasks
- | for your Laravel application. By default, we are compiling the Sass
+ | for your Laravel application. By default, we are compiling the Less
  | file for our application, as well as publishing vendor resources.
  |
  */