Remove [Slack][slack] message [formatting][formatting] 

[slack]: https://slack.com/
[formatting]: https://api.slack.com/docs/formatting

Library version of [this code][code].

[code]: https://github.com/slackhq/hubot-slack/blob/596c4181ccb9f8423c15077e3df2e960cd9981eb/src/slack.coffee#L174-L213

Usage

``js
const slack = require('@slack/client')
const makeRemoveFormatting = require('slack-remove-formatting')

const rtm = new slack.RtmClient(config.token)

rtm.on(slack.CLIENT_EVENTS.RTM.AUTHENTICATED, state => {
const removeFormatting = makeRemoveFormatting(state)

rtm.on(slack.RTM_EVENTS.MESSAGE, message => {
const text = removeFormatting(message.text)
console.log(text)
})
})
``