Add keys to all locales

[alexmarles]

Hi everyone,

maybe there is an option to do this, but I didn't find it in the readme:

Background: When I add a translation key to my app, I do it in order to translate a text into multiple languages, so the key has to be in all the locale files in my app.

To do: Instead of asking for a locale where to include the key, add the key to all locale files.

Thanks!