Fix figure captions to prevent going them to the next page without captions

Images can be used without captions and all the text is moved below the image if it does not fit into the page. However, figures are smarter with captions and only **they** are moved if they do not fit the current page whereas the text stays where it was.

We should use `image` if we do not have a caption and specify the image as `Like the image below:`. Otherwise, in the generated PDF we see those images in the next pages.

See the report [here](https://bitbucket.org/birkenfeld/sphinx/issue/1482/forcing-images-to-be-seen-in-the-same-page).