Multi language for default buttons

[MarcoDuizer]

Here it should use Yii::t('app','title') so its is multi language.

public $default_buttons = [ 'prev' => ['title' => 'Previous', 'options' => [ 'class' => 'btn btn-default', 'type' => 'button']], 'next' => ['title' => 'Next', 'options' => [ 'class' => 'btn btn-default', 'type' => 'button']], 'save' => ['title' => 'Save', 'options' => [ 'class' => 'btn btn-default', 'type' => 'button']], 'skip' => ['title' => 'Skip', 'options' => [ 'class' => 'btn btn-default', 'type' => 'button']], ];

[drsdre]

If you can send a pull request specific to multi-language, I will merge it quickly.