Update attribute visibility

 * Implement scenario() method similar to Yii2
 * Make all attributes visible by default
 * Add hiddenAttributes() method to hide specific attributes
Changed scenarios() default behavior
Merge pull request #37 from codemix/refactor-attribute-visibility

Update attribute visibility
Add pjax support, add local event stream
Fix safeAttributes bug in search()
Merge pull request #40 from codemix/fix-safe-attributes

Fix safeAttributes bug in save()
optionally qualify attribute names
support array format type
fix merge conflicts