Add format support

[jpomykala]

Hey,
could you add support for format like below?

{
  "de": {
    "SALE": "Verkauf",
    "ADDRESS": "Adresse"
  },
  "fr": {
    "SALE": "soldes",
    "ADDRESS": "adresse"
  }
}

• it's easier to provide messages for just one language by taking just a part of the JSON
• overall JSON with messages is much smaller, because you are not repeating locale key for each translation key
• it's a more common format for translation hosting 👍

[DRFR0ST]

Hi, thanks for your comment. We are planning to introduce a flexible format support later this year.