Update TinySluggableBehavior.php

Prevents error like:

Strict (2048): Declaration of TinySluggableBehavior::setup() should be compatible with ModelBehavior::setup(Model $model, $config = Array) [APP/Plugin/Utils/Model/Behavior/TinySluggableBehavior.php, line 138]
Strict (2048): Declaration of TinySluggableBehavior::beforeSave() should be compatible with ModelBehavior::beforeSave(Model $model) [APP/Plugin/Utils/Model/Behavior/TinySluggableBehavior.php, line 138]
Strict (2048): Only variables should be passed by reference [CORE/Cake/Model/BehaviorCollection.php, line 150]