Package users can now provide extra CSR extensions to serve certificates with desired properties. Fixes golang/go#17801. Change-Id: Iac1010f41391c865f6e318bad2e0dafc2ffef6b1 Reviewed-on: https://go-review.googlesource.com/42470 Reviewed-by: Adam Langley <agl@golang.org> Run-TryBot: Adam Langley <agl@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org>