Adding engine_version to elasticache replication group arguments (#12)

* adding engine_version to elasticache replication group

* changing default engine_version to 4.0.10

This is the newest available engine version available for Redis Elasticache.

* setting default family to redis4.0

main.tf

@@ -61,6 +61,7 @@ resource "aws_elasticache_replication_group" "default" {
   security_group_ids            = ["${aws_security_group.default.id}"]
   maintenance_window            = "${var.maintenance_window}"
   notification_topic_arn        = "${var.notification_topic_arn}"
+  engine_version                = "${var.engine_version}"
 
   tags = "${module.label.tags}"
 }

variables.tf

@@ -45,11 +45,11 @@ variable "instance_type" {
 }
 
 variable "family" {
-  default = "redis3.2"
+  default = "redis4.0"
 }
 
 variable "engine_version" {
-  default = "3.2.4"
+  default = "4.0.10"
 }
 
 variable "notification_topic_arn" {