ARROW-2682: [CI] Notify in Slack about broken builds
ARROW-2682: [CI] Notify in Slack about broken builds

Author: Korn, Uwe <Uwe.Korn@blue-yonder.com>

Closes #2121 from xhochy/ARROW-2682 and squashes the following commits:

b6fe8561 <Korn, Uwe> ARROW-2682:  Notify in Slack about broken builds

cpcloud/arrow,itaiin/arrow,majetideepak/arrow,majetideepak/arrow,wesm/arrow,xhochy/arrow,cpcloud/arrow,pcmoritz/arrow,itaiin/arrow,itaiin/arrow,pcmoritz/arrow,xhochy/arrow,renesugar/arrow,xhochy/arrow,renesugar/arrow,kou/arrow,renesugar/arrow,laurentgo/arrow,apache/arrow,itaiin/arrow,apache/arrow,xhochy/arrow,apache/arrow,laurentgo/arrow,laurentgo/arrow,majetideepak/arrow,wesm/arrow,pcmoritz/arrow,pcmoritz/arrow,wesm/arrow,cpcloud/arrow,laurentgo/arrow,icexelloss/arrow,apache/arrow,laurentgo/arrow,laurentgo/arrow,pcmoritz/arrow,cpcloud/arrow,pcmoritz/arrow,tebeka/arrow,kou/arrow,pcmoritz/arrow,apache/arrow,xhochy/arrow,itaiin/arrow,xhochy/arrow,wesm/arrow,pcmoritz/arrow,cpcloud/arrow,cpcloud/arrow,laurentgo/arrow,wesm/arrow,renesugar/arrow,laurentgo/arrow,renesugar/arrow,apache/arrow,apache/arrow,icexelloss/arrow,xhochy/arrow,wesm/arrow,pcmoritz/arrow,cpcloud/arrow,itaiin/arrow,pcmoritz/arrow,pcmoritz/arrow,cpcloud/arrow,pcmoritz/arrow,icexelloss/arrow,cpcloud/arrow,wesm/arrow,icexelloss/arrow,majetideepak/arrow,itaiin/arrow,tebeka/arrow,laurentgo/arrow,renesugar/arrow,tebeka/arrow,xhochy/arrow,icexelloss/arrow,kou/arrow,renesugar/arrow,icexelloss/arrow,xhochy/arrow,itaiin/arrow,tebeka/arrow,majetideepak/arrow,laurentgo/arrow,kou/arrow,kou/arrow,apache/arrow,icexelloss/arrow,kou/arrow,apache/arrow,itaiin/arrow,kou/arrow,cpcloud/arrow,laurentgo/arrow,majetideepak/arrow,cpcloud/arrow,kou/arrow,majetideepak/arrow,wesm/arrow,renesugar/arrow,wesm/arrow,xhochy/arrow,pcmoritz/arrow,tebeka/arrow,majetideepak/arrow,xhochy/arrow,cpcloud/arrow,laurentgo/arrow,wesm/arrow,pcmoritz/arrow,itaiin/arrow,wesm/arrow,kou/arrow,itaiin/arrow,majetideepak/arrow,majetideepak/arrow,laurentgo/arrow,laurentgo/arrow,pcmoritz/arrow,wesm/arrow,kou/arrow,majetideepak/arrow,tebeka/arrow,xhochy/arrow,laurentgo/arrow,kou/arrow,renesugar/arrow,tebeka/arrow,kou/arrow,renesugar/arrow,icexelloss/arrow,majetideepak/arrow,majetideepak/arrow,wesm/arrow,cpcloud/arrow,wesm/arrow,apache/arrow,icexelloss/arrow,apache/arrow,cpcloud/arrow,itaiin/arrow,kou/arrow,majetideepak/arrow,kou/arrow,renesugar/arrow,icexelloss/arrow,apache/arrow,xhochy/arrow,icexelloss/arrow,icexelloss/arrow,renesugar/arrow,apache/arrow,renesugar/arrow,xhochy/arrow,tebeka/arrow,itaiin/arrow,renesugar/arrow,icexelloss/arrow,tebeka/arrow,apache/arrow,itaiin/arrow,icexelloss/arrow,xhochy/arrow,itaiin/arrow,majetideepak/arrow,tebeka/arrow,renesugar/arrow