Save Accept-Language in the push notification Devices

Gijs Hendriksen
2018-03-14T17:48:22+01:00

This saves the the language of a push notification device by using the `Accept-Language` header sent with an api call to `/api/v1/devices/`.

This way, any device that registers for push notifications can immediately communicate their preferred language. If the preferred language is not available, it will fall back to English.