Remove the need for deal owners to have Slack users

Mikk Märtmaa

Hi, currently, in order to make a notification happen in Slack, the deal owner needs to have the Slack app installed and connected. 

This brings up a huge disadvantage of not being able to set up notifications for other team members (or teams) who do not have Slack installed and it leaves the team blind about general updates related to this user. 

We also use a generic user (not a person's account), who gets deals assigned automatically, since this account is not related to a person and their Slack account, we're not able to post notifications about this user's updates to deals.