[GEODE-160] Modify Git workspace check to use '--is-inside-working-tree' git command
[GEODE-160] Modify Git workspace check to use '--is-inside-working-tree' git command

Tested with using Git checkout and outside Git workspace using git archive

deepakddixit/incubator-geode,PurelyApplied/geode,PurelyApplied/geode,fengshao0907/incubator-geode,charliemblack/geode,davinash/geode,jdeppe-pivotal/geode,ysung-pivotal/incubator-geode,pivotal-amurmann/geode,mattcaldwell/incubator-geode,PurelyApplied/geode,smanvi-pivotal/geode,sshcherbakov/incubator-geode,davebarnes97/geode,prasi-in/geode,masaki-yamakawa/geode,davinash/geode,reshmik/incubator-geode,davinash/geode,smgoller/geode,sshcherbakov/incubator-geode,robertgeiger/incubator-geode,reshmik/incubator-geode,smgoller/geode,prasi-in/geode,shankarh/geode,reshmik/incubator-geode,charliemblack/geode,zuowang/incubator-geode,nchandrappa/incubator-geode,masaki-yamakawa/geode,charliemblack/geode,masaki-yamakawa/geode,smanvi-pivotal/geode,deepakddixit/incubator-geode,masaki-yamakawa/geode,reshmik/incubator-geode,jdeppe-pivotal/geode,zuowang/incubator-geode,ysung-pivotal/incubator-geode,mattcaldwell/incubator-geode,deepakddixit/incubator-geode,davebarnes97/geode,pdxrunner/geode,jdeppe-pivotal/geode,nchandrappa/incubator-geode,pivotal-amurmann/geode,robertgeiger/incubator-geode,shankarh/geode,zuowang/incubator-geode,prasi-in/geode,masaki-yamakawa/geode,charliemblack/geode,ysung-pivotal/incubator-geode,smgoller/geode,masaki-yamakawa/geode,robertgeiger/incubator-geode,davebarnes97/geode,smgoller/geode,pdxrunner/geode,pdxrunner/geode,davebarnes97/geode,deepakddixit/incubator-geode,sshcherbakov/incubator-geode,davebarnes97/geode,deepakddixit/incubator-geode,mattcaldwell/incubator-geode,deepakddixit/incubator-geode,pdxrunner/geode,davinash/geode,PurelyApplied/geode,pdxrunner/geode,davebarnes97/geode,fengshao0907/incubator-geode,pivotal-amurmann/geode,mattcaldwell/incubator-geode,smanvi-pivotal/geode,davinash/geode,zuowang/incubator-geode,robertgeiger/incubator-geode,nchandrappa/incubator-geode,sshcherbakov/incubator-geode,pivotal-amurmann/geode,masaki-yamakawa/geode,jdeppe-pivotal/geode,prasi-in/geode,charliemblack/geode,pivotal-amurmann/geode,PurelyApplied/geode,shankarh/geode,deepakddixit/incubator-geode,fengshao0907/incubator-geode,davinash/geode,smanvi-pivotal/geode,prasi-in/geode,PurelyApplied/geode,smgoller/geode,shankarh/geode,davinash/geode,pdxrunner/geode,jdeppe-pivotal/geode,ysung-pivotal/incubator-geode,smanvi-pivotal/geode,fengshao0907/incubator-geode,nchandrappa/incubator-geode,shankarh/geode,jdeppe-pivotal/geode,smgoller/geode,davebarnes97/geode,smgoller/geode,jdeppe-pivotal/geode,PurelyApplied/geode,pdxrunner/geode