The library should ship with a CA cert whitelist

[andrewmbenton]

The library currently ships with the specific Twilio server cert served by the Twilio API, effectively pinning that cert to the library. This is bad, since the library will break when the API changes certs after expiration or invalidation.

The library should ship with a standard CA cert whitelist such as the one here: http://curl.haxx.se/docs/caextract.html

[kevinburke]

agreed, will try to figure out a way to test this change today.