test: check for openssl cli and provide path if it exists

the previous version checked if io.js was compiled with openssl support which
isn't really relevant since we're starting a http server. we on the other hand
need an openssl-cli which may or may not exist.

PR-URL: https://github.com/iojs/io.js/pull/1049


Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Shigeki Ohtsu <ohtsu@iij.ad.jp>