Squashed commit of the following:

    Tweaks

    Extend test adding more assertions

    Update scaffold generator test and add application generator test for controller generator with namespace

    Adapt code to feedback suggestions

    Apply suggestions from code review

    Run generated tests by scaffold controller generator

    Fix generated tests too

    Keep generated url helpers consistent

    Fix scaffold controller generator with namespace

    For example:

    ```
    bundle exec rails g scaffold_controller Admin::Post title:string content:text --model-name=Post
    ```

    It fixes the code generated by railties, other changes are required on
    jbuilder gem.

Co-authored-by: Jonathan Hefner <jonathan@hefner.pro>
Co-authored-by: José Galisteo <ceritium@gmail.com>