tools: update certdata.txt

This is the latest certdata.txt from [0], last updated on 2015-04-20.

[0] https://hg.mozilla.org/mozilla-central/raw-file/aa275ad846f1/security/nss/lib/ckfw/builtins/certdata.txt

PR-URL: https://github.com/nodejs/io.js/pull/1833


Reviewed-By: Shigeki Ohtsu <ohtsu@iij.ad.jp>