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

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

Using str on Comments object will generate an encoded-str in python2,
which will fail when concatenated to a unicode.

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

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

refs #803

closes #1139

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

refs #806