Added progress writing to git checkout logic.
Added progress writing to git checkout logic.

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