Added client-side file validator
Fixed typo and inconsistent conditionals
Changed Array.prototype.slice.call() into jQuery's $.each function for consistency
Fixes #4360: Added client validation support for file validator
\yii\behaviors\AttributeBehavior updated
\yii\behaviors\BlameableBehavior updated
\yii\behaviors\TimestampBehavior updated
\yii\behaviors\SluggableBehavior updated
\yii\behaviors\TimestampBehavior updated
Fixes #3957: Added more straightforward configurable properties to `BlameableBehavior`, `SluggableBehavior` and `TimestampBehavior`