Update login.php (#87)

It's more consistent definition

views/site/login.php

@@ -17,7 +17,7 @@ $this->params['breadcrumbs'][] = $this->title;
 
     <?php $form = ActiveForm::begin([
         'id' => 'login-form',
-        'options' => ['class' => 'form-horizontal'],
+        'layout' => 'horizontal',
         'fieldConfig' => [
             'template' => "{label}\n<div class=\"col-lg-3\">{input}</div>\n<div class=\"col-lg-8\">{error}</div>",
             'labelOptions' => ['class' => 'col-lg-1 control-label'],