Create new mailman lists with the users language

When a new e-mail list is created il should have the users language as the default language

It's very compliacated for a non english speaking customer to change the language in mailman.

Here is the procedure :

1) Click on language

2) Tick the language you want to use

3) Save

4) Set default language to the new language

5) Save

This procedure is not obvious for beginners and having mailman directly in their native language would make it much easier for them to start off.