changed dateformat for %Y.%m.%d

Elasticsearch curator expects index with timestring with dots, https://github.com/Mirantis/reclass-system-salt-model/blob/master/elasticsearch/server/curator.yml#L29

Change-Id: I46d5fa0be82a7916c1055944b9a153a5e78044ec
diff --git a/fluentd/files/match/elasticsearch.conf b/fluentd/files/match/elasticsearch.conf
index ff015c8..f5024c5 100644
--- a/fluentd/files/match/elasticsearch.conf
+++ b/fluentd/files/match/elasticsearch.conf
@@ -8,7 +8,7 @@
   time_key_exclude_timestamp true
   logstash_format true
   logstash_prefix {{ values.get("es_index_name", "log") }}
-  logstash_dateformat %Y%m%d
+  logstash_dateformat %Y.%m.%d
   flush_interval {{ values.get("flush_interval", "10s") }}
   request_timeout {{ values.get("request_timeout", "10s") }}
 {%- if values.get("buffer") %}