Need implementation to send to user by user_id, from bot, not by slackbot

[ans-4175]

Where postMessageToUser(name, message [, params, callback]) (return: promise) - posts a direct message by user name I need to implement somekind like postMessageToUserId(user_id, message [, params, callback]) (return: promise) - posts a direct message by user id

But postMessage(id, text, params) sent as slackbot, not as current bot. Can we have it implemented?

[ans-4175]

I make PR for this, kindly check for it https://github.com/mishk0/slack-bot-api/pull/53 ?