French translation

Hello
I've translated the server messages in French. In order to learn git, I created a fork and a distinctive branch for those 2 files (mo+po). So I can propose a "pull request" (would be my very first one) or can send you the files somehow.
I haven't tested those l10n files as I'm still trying to figure out how to set the server in FR.

Thanks for cherrymusic! I like it :+1: 