Display preview logo

[pestevez]

With #162, the tool is showing the preview using data:text/html;charset=utf-8,${encodeURIComponent(contentHtml)} (Source).

With this change, we lost the ability to show the preview design logo, since it was using a relative address:

<amp-img src="preview-logo.png" width="206" height="44"></amp-img>

We should look for a way to keep the data:text/html optimization and to keep the logo. One simple way would be to return from the preview webserver an image that contains the full URL where it is available.

Before

After