title: Allow my own class in Rails to be configured with block syntax
body: <p>I often see code of the form</p>
  
  <pre><code>RSpec.configure do |config|
    config.include ApiHelper
  
    # ## Mock Framework
    #
    # If you prefer to use mocha, flexmock or RR, uncomment the appropriate line:
    #
    # config.mock_with :mocha
    # config.mock_with :flexmock
    # config.mock_with :rr
  
    # Remove this line if you're not using ActiveRecord or ActiveRecord fixtures
    config.fixture_path = "#{::Rails.root}/spec/fixtures"
  
    # If you're not using ActiveRecord, or you'd prefer not to run each of your
    # examples within a transaction, remove the following line or assign false
    # instead of true.
    config.use_transactional_fixtures = true
  
    # If true, the base class of anonymous controllers will be inferred
    # automatically. This will be the default behavior in future versions of
    # rspec-rails.
    config.infer_base_class_for_anonymous_controllers = false
  
    config.include FactoryGirl::Syntax::Methods
  
  end
  </code></pre>
  
  <p>Is there a feature in Rails that lets me do something similar? I want to be able to configure my own library with a similar syntax within config/initializers/my_class.rb</p>
  
  <pre><code>MyClass.configure do |config|
    # allow configuration here
  end
  </code></pre>