Reuse weboob.capabilities.image.BaseImage to contain the image and its
thumbnail.

TODO: image data should be fetched by modules by fillobj means

This will avoid importing lxml and requests in weboob.capabilities.*

Also, add Comment in weboob.capabilites.recipe.__all__.

Like cookboob does.

python modernize.py --no-six -f libmodernize.fixes.fix_print -w

With manual fixes as the import was put always on top.

refs #803

autopep8 -i --select=W602
Also some other minor deprecated syntax changes, like "while 1".
I did not commit the less obvious changes.