*: reflow comments to 80 characters

This reformats the entire Metropolis codebase to have comments no longer
than 80 characters, implementing CR/66.

This has been done half manually, as we don't have a good integration
between commentwrap/Bazel, but that can be implemented if we decide to
go for this tool/limit.

Change-Id: If1fff0b093ef806f5dc00551c11506e8290379d0
diff --git a/metropolis/pkg/pki/certificate.go b/metropolis/pkg/pki/certificate.go
index ff60f73..c0a1f53 100644
--- a/metropolis/pkg/pki/certificate.go
+++ b/metropolis/pkg/pki/certificate.go
@@ -37,7 +37,8 @@
 	prefix string
 }
 
-// Namespaced creates a namespace for storing certificate data in etcd at a given 'path' prefix.
+// Namespaced creates a namespace for storing certificate data in etcd at a
+// given 'path' prefix.
 func Namespaced(prefix string) Namespace {
 	return Namespace{
 		prefix: prefix,
@@ -91,7 +92,7 @@
 
 // Client makes a Kubernetes PKI-compatible client certificate template.
 // Directly derived from Kubernetes PKI requirements documented at
-// https://kubernetes.io/docs/setup/best-practices/certificates/#configure-certificates-manually
+//   https://kubernetes.io/docs/setup/best-practices/certificates/#configure-certificates-manually
 func Client(identity string, groups []string) x509.Certificate {
 	return x509.Certificate{
 		Subject: pkix.Name{