Slack notifications are only to indviduals

[russellseymour]

Notifications are only targetted at the individual that created the resource group.

Need to add a new tag that will allow a channel, or channels, to be specified. This will then be used to identify a group of users about impending shutdowns or deletions rather than the indvidual.

If this tag has been set then the notification will not be sent to the indivdual.