Add option to disable networking (or have it off by default). Basically, we want to prevent a job from accessing the internet if we want repeatable builds and/or are doing a downstream build somewhere else. Other/downstream build environments often have networking off. Copr has an option: (See: https://lists.fedorahosted.org/archives/list/copr-devel@lists.fedorahosted.org/thread/LZZPJ534ZDRD7YYFDC3BXDUVVPF5B735/ )

In particular, the ovirt-engine-nodejs-modules build-artifacts job tries to stay offline, but an evil node module called 'phantomjs' connects to the internet in a post-offline-install hook. I'd like the option to disallow that and have the build fail.