Add ability to change keepalive_timeout parameter value

Fixes: PROD-32426
Change-Id: I558aa438bc0ef30a37301ca81d42ec02f9df871d
diff --git a/nginx/files/nginx.conf b/nginx/files/nginx.conf
index 9429740..991e662 100644
--- a/nginx/files/nginx.conf
+++ b/nginx/files/nginx.conf
@@ -19,7 +19,7 @@
         sendfile on;
         tcp_nopush on;
         tcp_nodelay on;
-        keepalive_timeout 65;
+        keepalive_timeout {{ server.get('keepalive_timeout', '65') }};
         types_hash_max_size 2048;
         server_tokens {% if server.get('tokens', False) %}on{% else %}off{% endif %};