Fix pk lookup in _setup_next_sequence method.

Closes #31

Signed-off-by: Raphaël Barrois <raphael.barrois@polyconseil.fr>
Add classmethod decorator to child factories methods

Closes #33,#34

Signed-off-by: Raphaël Barrois <raphael.barrois@polyconseil.fr>
Fix version numbering.

Somehow, I forgot that I had release 1.2.0 :/

Signed-off-by: Raphaël Barrois <raphael.barrois@polyconseil.fr>
Happy New Year!

Signed-off-by: Raphaël Barrois <raphael.barrois@polytechnique.org>