Tests fails when default language is not english

[petitchevalroux]

To reproduce :

export LC_ALL="fr_FR.UTF-8"

npm run tester

I tried to set and export before scripts in package.json without succeed.

Its related to : https://github.com/strongloop/strong-globalize https://github.com/sindresorhus/os-locale/

Which use the default environnement variable + the fact that errors.js use error message to override 500 behaviour