test: fix parallel/test-http-destroyed-socket-write2

Ameliorate a timing sensitivity issue by switching from setImmediate()
to setTimeout() with a 50 ms timeout.

This commit also adds EPIPE as an accepted error (besides ECONNABORT
and ECONNRESET) because that's a plausible outcome given the timing
sensitive nature of test.

PR-URL: https://github.com/iojs/io.js/pull/575


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Fedor Indutny <fedor@indutny.com>