This fixes a bug related to the way we made joins to query q postgresql db.
I found that we didn't needed at all any join, so a simple lookup in the m2m relation table allows to speed up things.
Fix#44
The only translation so far is french, but more can be added. The browser language
is used thanks to the HTTP languages headers.
There are still some problems with the translation of some strings, I don't know
why this is. See #12
* web.py contains the controllers (also called views) + url definitions
* models.py contains the models
* forms.py contains the forms
* utils.py contains a set of utility fonctions to ease the dev. process