send slack notification on failure
send slack notification on failure

[#159245407]

cloudfoundry-incubator/cli-plugin-repo,cloudfoundry-incubator/cli-plugin-repo,cloudfoundry-incubator/cli-plugin-repo,kkellner/cli-plugin-repo,kkellner/cli-plugin-repo,kkellner/cli-plugin-repo,cloudfoundry-incubator/cli-plugin-repo