Add french localization

Add french localization.

Note that when I open the project with Xcode 4.6.1 I have all localized files marked red as if Xcode didn't find the files on my drive. The projects compiles just fine however.

![Xcode red localized files](https://f.cloud.github.com/assets/1041337/351561/a045bba0-a04d-11e2-906c-a9dd655b2beb.png)