tarfile.add doesn't take anymore 'exclude' keyword anymore but 'filter'
can do the same in both py2 and py3.
Also, subprocess returns bytes.

TODO this is less efficient on python2

gpg2 generates a keyring with the keybox format, which is only supported
by gnupg >=2.1

Current gpgv has a bug where the gpgv command does not work

A patch has already been sent upstream :
https://lists.gnupg.org/pipermail/gnupg-devel/2015-December/030623.html

Using gpg --verify rather than gpgv fixes the issue.
If gpg is not found, gpgv is used as a fallback.

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.

refs #806

"line" redefined in list comprehension.

and PEP8 indent fixes

This is recommended by Debian.
closes #618

I used autopep8 on some files and did carefully check the changes.
I ignored E501,E302,E231,E225,E222,E221,E241,E203 in my search, and at
least E501 on any autopep8 run.

Other style fixes not related to PEP8:
* Only use new-style classes. I don't think the usage of old-style
  classes was voluntary. Old-style classes are removed in Python 3.
* Convert an if/else to a one-liner in mediawiki, change docstring style
  change to a comment something that wasn't really appropriate for a
  docstring.
* Unneeded first if condition in meteofrance

There is no reason to hide it from anyone, the GPG default is not
appropriate in our case.

stderr is shown and an exception is raised if GPG does not exit
successfully.

* Use directories mtime (so deleted or renamed files are taken into account)
* Set the tarfile mtime close to the version