Revert "test: don't assume broadcast traffic is unfiltered"

This reverts commit 52e600a9.

Reverted for:

* making the test fail with ENETUNREACH on OS X 10.8, and

* making the test fail with EHOSTDOWN on OS X 10.9 and 10.10 when there
  is no network connectivity, and

* leaving behind orphan processes that make subsequent tests fail with
  EADDRINUSE errors

PR-URL: https://github.com/iojs/io.js/pull/259


Reviewed-By: Rod Vagg <rod@vagg.org>