Add real visual tests

[AMorgaut]

The main goal of this project is to reach the best possible representation of EFL views in the Browser

So the most important tests are ones that validate the visual rendering of the provided components.
because created via the nwb tool, I submitted a feature request there.

In the meantime I'll test different options until validation gets sastifying

Here the currently found solutions:

• PhantomCSS
• Headless Chrome + dom-to-image + Resemble.js
• loki

[AMorgaut]

storybook looks interesting