Install to 64bit Windows by setup.sh

Formerly failed because its "platform" variable's value is "windows_amd64" and there is no binaries for it.
Remove a bad configuration in build.gradle, which forces a build in Windows/amd64 use cross-compilation for 386
Use Gradles' exec task instead of ProcessBuilder because the former implementation doesn't work in Windows (no output on failure)

And removed --debug option from arguments of groovyserver because it causes infinitely blocking of a build process.
Use stderr for warning or dump in Go