title: Form validation message with aliased attribute name
body: <p>I'm using Stripe within a model class. I have a <code>strike_token</code> attribute that I am validating presences of and creating a custom message like so:</p>
  
  <pre><code>validates :stripe_token, presence: { message: 'Please enter valid card info' }
  </code></pre>
  
  <p>When the form is submitted and not valid, the error message is, "Stripe token Please enter valid card info"</p>
  
  <p>I don't want Stripe token in the error message. I have other validations as well that would be suited for the default, so I don't want to change the default error behavior.</p>
  
  <p>It would be better if I could alias the Stripe token attribute to something like <code>:card_info</code> without actually having that as an attribute on the model.</p>
  
  <p>So the message could be made to read, "Card info cannot be blank"</p>