Application Load Balancers - aws-sdk-go wrapper layer

[diemonster]

Wrapper code for consuming the elbv2 aws-sdk-go API. This can largely mimic the existing code in /common/aws/elb, although we will need additional methods to support Target Groups, etc.

AWS ALB API Reference: http://docs.aws.amazon.com/elasticloadbalancing/latest/APIReference/Welcome.html https://github.com/aws/aws-sdk-go/blob/master/service/elbv2/api.go

We'll also need to update the necessary models elbv2 in /common/models.