Add DNS to subjectAltName in Self-Signed Certificate

According to [1]:
IP address used in the IP options can be in either IPv4 or IPv6 format.
DNS can be used for IPv4 only, IPv6 only and dual stack.

Also should have FQDNs in subjectAltName per current[2].

[1] https://www.openssl.org/docs/man1.0.2/man5/x509v3_config.html
[2] https://support.google.com/chrome/a/answer/7391219

Partially-Implements: blueprint ipv6-control-plane

Change-Id: Ibad8f8c734984aeda8ddac1a5db39875bc242bbf