Initiate async download of a locale

curl "https://api.phrase.com/v2/projects/:project_id/locales/:locale_id/downloads" \
  -u USERNAME_OR_ACCESS_TOKEN \
  -X POST \
  -d '{"branch":"my-feature-branch","file_format":"yml","tags":"feature1,feature","custom_metadata_filters":{"tone":"friendly"}}' \
  -H 'Content-Type: application/json'

{
  "id": "abcd1234cdef1234abcd1234cdef1234",
  "status": "completed",
  "result": {
    "url": "https://example.com/locales/abcd1234cdef1234abcd1234cdef1234/download?file_format=yml"
  },
  "params": {
    "file_format": "yml",
    "locale_id": "abcd1234cdef1234abcd1234cdef1234",
    "tags": "feature1,feature2",
    "branch": "my-feature-branch",
    "include_empty_translations": true,
    "include_translated_keys": true,
    "include_unverified_translations": true
  },
  "created_at": "2015-01-28T09:52:53Z",
  "completed_at": "2015-01-28T09:52:53Z"
}