Fix #905: web hook should have Content-Type application/json
Fix #905: web hook should have Content-Type application/json

bbauya/kudu,chrisrpatterson/kudu,puneet-gupta/kudu,badescuga/kudu,juvchan/kudu,shrimpy/kudu,mauricionr/kudu,bbauya/kudu,chrisrpatterson/kudu,MavenRain/kudu,sitereactor/kudu,chrisrpatterson/kudu,YOTOV-LIMITED/kudu,barnyp/kudu,kenegozi/kudu,MavenRain/kudu,YOTOV-LIMITED/kudu,puneet-gupta/kudu,juvchan/kudu,badescuga/kudu,shibayan/kudu,shibayan/kudu,EricSten-MSFT/kudu,shrimpy/kudu,kenegozi/kudu,kenegozi/kudu,shrimpy/kudu,EricSten-MSFT/kudu,projectkudu/kudu,EricSten-MSFT/kudu,badescuga/kudu,projectkudu/kudu,uQr/kudu,juoni/kudu,duncansmart/kudu,sitereactor/kudu,mauricionr/kudu,uQr/kudu,bbauya/kudu,dev-enthusiast/kudu,bbauya/kudu,kenegozi/kudu,puneet-gupta/kudu,dev-enthusiast/kudu,juoni/kudu,EricSten-MSFT/kudu,sitereactor/kudu,barnyp/kudu,duncansmart/kudu,badescuga/kudu,duncansmart/kudu,shibayan/kudu,juvchan/kudu,puneet-gupta/kudu,oliver-feng/kudu,sitereactor/kudu,puneet-gupta/kudu,kali786516/kudu,juoni/kudu,uQr/kudu,barnyp/kudu,juvchan/kudu,badescuga/kudu,mauricionr/kudu,kali786516/kudu,mauricionr/kudu,sitereactor/kudu,oliver-feng/kudu,uQr/kudu,chrisrpatterson/kudu,barnyp/kudu,projectkudu/kudu,dev-enthusiast/kudu,juvchan/kudu,shibayan/kudu,MavenRain/kudu,YOTOV-LIMITED/kudu,dev-enthusiast/kudu,shrimpy/kudu,shibayan/kudu,MavenRain/kudu,juoni/kudu,oliver-feng/kudu,EricSten-MSFT/kudu,projectkudu/kudu,kali786516/kudu,projectkudu/kudu,oliver-feng/kudu,YOTOV-LIMITED/kudu,duncansmart/kudu,kali786516/kudu