Update CA roots ".pem" file

Summary: We're nearly a year out of date. Downloaded a fresh one from http://curl.haxx.se/docs/caextract.html

Test Plan: diffed them, saw sensible-looking changes

Reviewers: btrahan, codeblock

Reviewed By: codeblock

CC: aran

Differential Revision: https://secure.phabricator.com/D4349