Only trigger ALB module if ALB != ‘none’ (#74)
If wanting to create an ECS task that does not have an ALB e.g. a
scheduled task of some kind that doesn’t need an ALB, because we try and
do a lookup on a data source, I am currently getting 
If load_balancing_type is set to none, take it that we do *not* want to
create any resources in the ALB module.
* module.ecs_service.module.alb_handling.data.aws_lb.main: 1 error occurred:
* module.ecs_service.module.alb_handling.data.aws_lb.main: data.aws_lb.main: Search returned 0 results, please revise so only one is returned
Minor bugfixing (#59)
* Fixed bug in custom exception and error reporting
* Added stack to custom error. Without it, error origin is lost.
* Changed Python string building to JS concatenation.
string modulo string gives a NaN result every time.
* Respect the health check grace period variable
* Statement actions MUST be lists in Terraform.