Provide a way to stay current with a terraform template

[jritsema]

As we make changes to the various terraform templates, it might be nice to provide an easy way to stay up to date with the latest changes, without having to manually piece together and apply the changes. Maybe something like this for the default web app template:

fargate-create upgrade

...and for other templates:

fargate-create upgrade -t git@github.com:turnerlabs/terraform-ecs-fargate-scheduled-task

It would warn you that it's going to add/overwrite your .tf files and prompt for yes/no. And then it would remind you to run terraform init and terraform apply.