title: How to disable $_accessible protection for admin in CakePHP 3?
body: <p>I was trying to do this pretty much time and now I quit.
  In CakePHP 3 there is protection against mass assignment vulnerability by setting in Entity variable $_accessible. It's helpful against hackers but it's also very annoying when you build admin panel.
  My question is how to disable this protection for all controllers with prefix="admin" and keep it for others?</p>
  
  <ul>
  <li>It can't be done in model beforeSave cause this is executed too late.</li>
  <li>I tried also create Behavior but it can't touch Entity, where things happen.</li>
  <li>The closest one was overwriting method newEntity() in a model but this way I must do it in every single model which is not very pretty solution.</li>
  <li>I know also it can be done in controller action when I'm saving data but writing it for every admin action... Well, there must be some better way.</li>
  </ul>