title: Disable a gem's Railtie initializer
body: <p>Is there a way to disable a railtie that is loaded by a gem by default ?</p>
  
  <p>The developers of the gem did not make it modular and once putting the gem in the Gemfile, the require will automatically load the railties this way:</p>
  
  <pre><code>require 'some_gem'
  
  module SomeGem
    module RailtieMixin
      extend ActiveSupport::Concern
  
      included do
        rake_tasks do
          require 'some_gem/rake_tasks'
        end
  
        initializer 'some_gem.configuration' do
          config.after_initialize do
            ...
          end
        end
  
        initializer 'some_gem.controller_methods' do
          ...
        end
      end
    end
  end
  </code></pre>
  
  <p>I'd like to have some control, and ideally disable only the <code>'some_gem.controller_methods'</code>, is it possible to do this ? without monkeypatching ? without patching the gem ?</p>