title: Pass current instance to validator in laravel
body: <p>In laravel 5.3 can I pass as parameter for rule current instance of model?</p>
  
  <p>I want the rule which checks current value of some field in my model and allows or denies to set this field to another value.</p>
  
  <p>The problem is: validator receives only new value, but I also want to check old value.</p>