title: validates_email_format_of throws Unknown validator: 'EmailFormatValidator' in rails 4 engines
body: <p>I am using rails 4, and I am I creating an engine. In this engines <code>.gemspec</code> I did the following:</p>
  
  <pre><code>  s.add_dependency "rails", "~&gt; 4.0.3"
    s.add_dependency 'pg'
    s.add_dependency 'bcrypt-ruby'
    s.add_dependency 'validates_email_format_of' #Hi I am right here
  
    s.add_development_dependency 'rspec-rails'
    s.add_development_dependency 'letter_opener'
    s.add_development_dependency 'pry'
    s.add_development_dependency 'pry-rails'
    s.add_development_dependency 'database_cleaner'
    s.add_development_dependency 'capybara'
    s.add_development_dependency 'factory_girl_rails'
  </code></pre>
  
  <p>I followed these <a href="https://github.com/alexdunae/validates_email_format_of#installation" rel="nofollow">instructions on installing</a> <code>validates_email_format_of</code> and the <code>bundle install</code> worked. How ever when I run <code>bundle exec rspec</code> I get the error:  <code>Unknown validator: 'EmailFormatValidator'</code></p>
  
  <p>My Model Looks Like this:</p>
  
  <pre><code>require 'bcrypt'
  
  module Xaaron
    class User &lt; ActiveRecord::Base
      attr_accessor :password
  
      before_save :encrypt_password
  
      validates :first_name, presence: true
      validates :user_name, uniqueness: true, presence: true, length: {minimum: 5}
      validates :email, presence: true, confirmation: true, uniqueness: true, email_format: {message: "Email Invalid"}, if: :new_record?
      validates :password, presence: true, confirmation: true, length: { minimum: 10 }, if: :new_record?
  
      def self.authenticate_user(user_name, password)
          user = Xaaron::User.find_by(user_name: user_name)
          if(user &amp;&amp; user.password_hash == BCrypt::Engine.hash_secret(password, user.salt))
              user
          else
              nil
          end
      end
  
      def encrypt_password
          if password.present?
              self.salt = BCrypt::Engine.generate_salt
              self.password_hash = BCrypt::Engine.hash_secret(password, salt)
          end
      end
    end
  end
  </code></pre>
  
  <p>See nice and simple, the line <code>validates :email, presence: true, confirmation: true, uniqueness: true, email_format: {message: "Email Invalid"}, if: :new_record?</code> is whats throwing the error. Now the docs state to use <code>:email_format =&gt; {message: 'asdasdsad'}</code> But no matter how the syntax is, I get that error.</p>
  
  <p>Thoughts?</p>