title: Devise lockable - How to unlock account using unlock_in
body: <p>Let me post what I have done first:</p>
  
  <pre><code>config.lock_strategy = :failed_attempt
  config.unlock_keys = [ :email ]
  config.unlock_strategy = :both
  config.maximum_attempts = 10
  config.unlock_in = 30.minutes
  </code></pre>
  
  <p>I have added all the fields in the respective table and added: lockable in model as well.</p>
  
  <p>The problem I am facing is, my account is getting locked upon 10 bad attempts, and Admin is able to log in and manually unlock it.</p>
  
  <p>However my 2nd scenario is, I need the account to be unlocked after 30min as I have specified.</p>
  
  <p>I need to know if I am supposed to be calling any separate method for unlock_in to work.</p>