Windows installers use the value of REGVER decide if Go is being upgr…

…aded/downgraded/no-change

For windows installations, a comparison of 'Ver' registry entry (from current installation) with the REGVER variable(from the version being installed) is done to determine if Go is being upgraded/downgraded/no-change. Hence, the value for this variable must he higher than the previous versions

buildSrc/src/main/groovy/com/thoughtworks/go/build/WindowsPackagingTask.groovy

@@ -131,7 +131,7 @@ class WindowsPackagingTask extends DefaultTask {
           'MODULE'           : packageName.replaceAll(/^go-/, ''),
           'GO_ICON'          : project.file('windows-shared/gocd.ico').absolutePath,
           'VERSION'          : "${version}-${distVersion}",
-          'REGVER'           : "${version}${distVersion.padRight(5, '0')}".replaceAll(/\./, ''),
+          'REGVER'           : "${version.split(/\./).collect{it.padLeft(2, '0')}.join()}${distVersion.padRight(5, '0')}",
           'JAVA'             : 'jre',
           'JAVASRC'          : jreDir,
           'DISABLE_LOGGING'  : System.getenv('DISABLE_WIN_INSTALLER_LOGGING') ?: false,