[20180527180826] Autoscaling and ALB Log Retention

[ddollar]

This release moves the autoscaler to a scheduled Lambda function and modifies the algorithm to ensure that there is always available space for new containers.

ALB logs are now also limited by the LogRetention rack parameter.

• #2685 autoscale via scheduled lambda [@ddollar]
• #2694 use proper autoscaling target for internal services [@ddollar]
• #2695 make LogRetention property also affect alb logs [@ddollar]