Add an Elasticsearch client

This patch adds a client. The client will be responsible to push new
indexes and new templates to Elasticsearch.
diff --git a/metadata/service/client.yml b/metadata/service/client.yml
new file mode 100644
index 0000000..1e5fbc1
--- /dev/null
+++ b/metadata/service/client.yml
@@ -0,0 +1,6 @@
+applications:
+- elasticsearch.client
+parameters:
+  elasticsearch:
+    client:
+      enabled: true