Change message for missing app in Slack messages
Change message for missing app in Slack messages

For Slack tracking messages. Tracking messages have no application
associated with them, so just add 'Iris incident' as default

jrgp/iris-api-opensource,dwang159/iris-api,linkedin/iris,jrgp/iris-api-opensource,linkedin/iris,dwang159/iris-api,jrgp/iris-api-opensource,jrgp/iris-api-opensource,linkedin/iris,linkedin/iris,dwang159/iris-api,dwang159/iris-api