[BUGFIX] Protect fields: "type" and "id"

Problem/Motivation

According with the spec, the fields type and id are protected and cannot appear in the attributes or the relationships. See: http://jsonapi.org/format/upcoming/#document-resource-object-fields

We do have type and id in our payloads.

Proposed resolution

Change the name of the property to a safe name. Suggestions are:

• entity--type and entity--id
• resource--type and resource--id
• …

Whenever we need to do a field change, we should note that in the metadata for that object:

{
  "type": "lorem--ipsum",
  "id": 1234,
  "attributes": {
    "resource--type": "foo"
  }
  "meta": {
    "fieldMaps": {
      "resource--type": "type"
    }
  }
}

That way consumers may build a matching representation of the object in the backend with the correct field names.