Load custom templates now working (via #37)

[PurHur]

This is the merged and fixed pull request #37. (#32)

To load a custom twig template you can define the path and the file via your behat configuration:

      render_options:
        twig_template_name: report.twig
        twig_template_path: templates/

[donkidd]

Should we start building & using tests in the classes?

[donkidd]

Can you add some documentation to the README.md file about this new template feature?

[PurHur]

We should And im gonna rework the readme

[PurHur]

I will reimplement this feature in the next time with a fresh and clean PR