Use kustomize and envsubst to generalize k8s config.

Adds a [kustomize](https://github.com/kubernetes-sigs/kustomize) overlay
for a new staging environment. Additionally, adds environment variables
in the place of certain pieces of information that need to be templated.

The K8s README ("deploy/README.md") has been updated to reflect the new
method for applying config.

This commit also removes the configuration for the AWS cluster and
references to AWS in the README.

deploy/azure/volume-claim.yml

@@ -0,0 +1,12 @@
+apiVersion: v1
+kind: PersistentVolumeClaim
+metadata:
+  name: crls-vol-claim
+  namespace: atat
+spec:
+  accessModes:
+    - ReadWriteMany
+  storageClassName: azurefile
+  resources:
+    requests:
+      storage: 1Gi