Update install script to work with older powershell versions
Update install script to work with older powershell versions

Azure/azure-devtestlab,Azure/azure-devtestlab,Azure/azure-devtestlab,marrobi/azure-devtestlab,mmydland/azure-devtestlab,marrobi/azure-devtestlab,Azure/azure-devtestlab,Azure/azure-devtestlab,mmydland/azure-devtestlab,mmydland/azure-devtestlab,marrobi/azure-devtestlab