Welcome message and optional dialog

[tkorakas]

When a new user joins introductions channel we'll:

• Send a welcome message
• Ask him if he want to answer some questions
• Save answers to spreadsheet

[tkorakas]

We need to enable "member_joined_channel" event and invite bot to channel.

[tkorakas]

It would be better to send DM to user when joins the workspace. Instead of member_joined_channel event I'll use team_join.

Example:

controller.on('team_join', function (bot, message) {
  bot.api.chat.postMessage({channel: response.channel.id, text: 'Welcome', as_user: true}, (err, response) => {
    // Process postMessage error and response
  })
})