docs: function do_json(url, opts) {
  	opts = opts || {};
  	if(is.object(opts) && is.defined(opts.body)) {
  		opts.body = JSON.stringify(opts.body);
  	}
  	opts.headers = opts.headers || {};
  	if(opts.body) {
  		opts.headers['Content-Type'] = 'application/json;charset=utf8';
  	}
  	opts.headers.Accept = 'application/json';
  	return do_plain(url, opts).then(function(buffer) {
  		return JSON.parse(buffer);
  	});
  }