Update README a little to document Terraform-based setup.
Don’t bother launching the Grafana container.
Update AMIs to CoreOS v438.0.0.

This releases includes an update cloud-init that
should support YAML merge. This means that etc
discovery URLs and fleet metadata can be dynamically
injected into the CoreOS cloud-config YAML via
Terraform variables and outputs. Yay!
Scope InfluxDB CNAME by environment.
Remove outdated Grafana config.
[terraform] Create S3 bucket and CNAME for Grafana.
Newest CoreOS release supports YAML merge. Use it!
Provide /etc/aws_environment for region, instance-id & keys.
Register InfluxDB with ELB load balancer name from Terraform.

TODO: stop distributing this to every node, so figure
out a better way to communicate from Terraform to
units.
Deploy Grafana to S3 via Terraform & awscli.
[terraform] Support generating random environment names.
[influxdb] Clean up units a little.
Use round-robin’d CNAME for InfluxDB.
Use CoreOS’ machine-id as sysinfo series prefix.

Also, set sampling to 10s interval.
We’re not using the Grafana container, but…

I tweaked a couple of things.