Improve new member onboarding

[tonymobster]

Currently when a new member joins the slack group we send a welcome message and invite them to update their slack profile. I think it would be a better experience if we initiate a private conversation afterwards and:

• give information on who we are and what we're about
• inform them of code of conduct
• give a quick slack tutorial
• inform of them who the admins are
• show them interesting channels to join
• inform them of our community projects
• ask more info about them and what they do and use the slack api to update their profile on their behalf, after getting the user's consent to do so

[bubunyo]

I don't think it is our place to give a quick slack tutorial.