This commit introduces the HTTP interface for the dynamic K8s node
provisioner. It will serve as the main communication point between the
ephemeral nodes in the cloud, sharing the keys and tokens they require
in order to join the Kubernetes cluster.
The initial functionality is simply an Amazon SNS notification receiver.
SNS notifications will be used to manage the lifecycle of the dynamic
nodes.
For now, the notification receiver handles subscription confirmation
messages by following the link provided to confirm the subscription.
All other messages are simply written to the filesystem; these will be
used to implement and test future functionality.
Dustin