Add option to clear routes when calling draw.

Applying the patch below will allow a plugin developer nicer access to adding routes in init.rb.

Instead of :

require 'dispatcher'
Dispatcher.to_prepare :foo_plugin_routes do
  map = ActionController::Routing::RouteSet::Mapper.new(ActionController::Routing::Routes)
  map.resources :postings do |postings|
    postings.resources :comments
  end
  ActionController::Routing::Routes.send(:install_helpers)
end

You can :

require 'dispatcher'
Dispatcher.to_prepare :foo_plugin_routes do
  ActionController::Routing::Routes.draw(false) do |map|
    map.resources :postings do |postings|
      postings.resources :comments
    end
  end
end