added buildArch option, console.log for errors

Great work on this, worked pretty well for me. 

The only problem I ran into was folder permissions on the /opt.. /tmp directory - it kept saying it could not access the temp file without sudo access. I don't know if it's due to the logic here, or due to the rpmbuild install process on mac that required sudo. I was able to fix it though by changing the permissions on the tmp dir.