use lowercase for service hostnames

Some applications seem sensitive to this. Most applications seem to
automatically lowercase, and some (e.g. ssh) will not match it up to the
uppercase form in /etc/hosts.

Signed-off-by: Alex Suraci <suraci.alex@gmail.com>

core/container.go

@@ -1857,7 +1857,7 @@ func hostHash(val digest.Digest) string {
 	if err != nil {
 		panic(err)
 	}
-	return b32(xxh3.Hash(b))
+	return strings.ToLower(b32(xxh3.Hash(b)))
 }
 
 func b32(n uint64) string {