Remove timeout feature and replace with unref().

The EphemeralSocket had a timeout feature build into it
    so that the statsd client doesn't keep a CLI program open.

This was implemented in a complicated way with timers, I've
    removed that complexity and replaced it with an unref() call.
Merge pull request #6 from uber/0.0.4-dns-recovery.cleanup-timeout

[DNS recovery]: Remove timeout feature and replace with unref().