Use nested JSON instead of dot strings

[universalmind303]

• The document structure should be nested JSON objects. If you use Beats or Logstash, the nesting of JSON objects is done for you automatically. If you’re ingesting to Elasticsearch using the API, your fields must be nested objects, not strings containing dots.
• See Why does ECS use a dot notation instead of an underline notation? for more details.

Some of us are using other tools to ingest to Elasticsearch. (Elasticsearch API, fluentd, kinesis streams) It would be nice if we did not have to provide additional parsing to get these logs into the nested json format.

[universalmind303]

appears to be a duplicate of #51