Embed Mozilla's Root CA set for use in Docker environments without CA files.

Thanks to Adam Langley and Kelsey Hightower for pointers:

https://github.com/kelseyhightower/contributors/blob/master/certs.go
https://medium.com/@kelseyhightower/optimizing-docker-images-for-static-binaries-b5696e26eb07
https://github.com/agl/extract-nss-root-certs

Change-Id: I440cedf476446da852c409958a877fbcdb464340