title: How to find users, keys to see the pictures on production and how to ban some users?
body: <p>I could see the pictures in production and  I've completed  Ruby on Rails tutorial by Michael Harti.</p>
  
  <p>How to ban some users?</p>
  
  <p>Should I store banned users in a new database table and then check it every time someone tried to register? 
  How to implement that? Maybe there is an another more simple and efficient  approach and implementation to bun some users?
  Would you please collaborate?
  thanks.</p>