Added hability to inspect nested routes [resolve #34]

First approach to inspect nested routes
I called root_path but it's the path where the application is mount, I give you an example:

```ruby
class MyLotusApp
  def call(env)
  end
  def routes
    Lotus::Router.new do
      get '/home', to: 'home#index'
    end
  end
end

router = Lotus::Router.new do
  mount MyLotusApp, at: /my_lotus_app
end
```
then the "root_path" is ```/my_lotus_app``` because I need to pass in line 70 to print the correct path ```/my_lotus_app/home``` and no print only ```/home```