Add support for choosing a language for method of obtaining amenities

[Konstantin Osipov]

Data can be downloaded in other languages:

English: /api/v2/static/amenities/en.json.
French: /api/v2/static/amenities/fr.json
German: /api/v2/static/amenities/de.json.
Spanish: /api/v2/static/amenities/es.json.