add a script that checks languages

[categulario]

This can help with #63. Maybe if added to a CI pipeline like travisCI or github actions, combined with a badge in the readme it won't be necessary to have this issue open.

I ran the script and it reported that french is not valid json btw

[J-Rios]

Hi, thanks for the contribution :)

The script is useful, however the issue also point to existing keys that could have a translated text from a previous version, so it should keep open as a notice to every one.

Best Regards.