Fix AWS region vs zone

We were specifying a region, but naming it as a zone in util.sh

The zone matters just as much as the region, e.g. for EBS volumes.

We also change the config to require a Zone, not a Region.
But we fallback to get the information from the metadata service.

cluster/aws/util.sh

@@ -21,7 +21,10 @@
 KUBE_ROOT=$(dirname "${BASH_SOURCE}")/../..
 source "${KUBE_ROOT}/cluster/aws/${KUBE_CONFIG_FILE-"config-default.sh"}"
 
-export AWS_DEFAULT_REGION=${ZONE}
+# This removes the final character in bash (somehow)
+AWS_REGION=${AWS_ZONE%?}
+
+export AWS_DEFAULT_REGION=${AWS_REGION}
 AWS_CMD="aws --output json ec2"
 AWS_ELB_CMD="aws --output json elb"
 
@@ -105,7 +108,7 @@ function detect-image () {
   # See here: http://cloud-images.ubuntu.com/locator/ec2/ for other images
   # This will need to be updated from time to time as amis are deprecated
   if [[ -z "${AWS_IMAGE-}" ]]; then
-    case "${ZONE}" in
+    case "${AWS_REGION}" in
       ap-northeast-1)
         AWS_IMAGE=ami-93876e93
         ;;
@@ -428,7 +431,7 @@ function kube-up {
     echo "readonly NODE_INSTANCE_PREFIX='${INSTANCE_PREFIX}-minion'"
     echo "readonly SERVER_BINARY_TAR_URL='${SERVER_BINARY_TAR_URL}'"
     echo "readonly SALT_TAR_URL='${SALT_TAR_URL}'"
-    echo "readonly AWS_ZONE='${ZONE}'"
+    echo "readonly AWS_ZONE='${AWS_ZONE}'"
     echo "readonly MASTER_HTPASSWD='${htpasswd}'"
     echo "readonly PORTAL_NET='${PORTAL_NET}'"
     echo "readonly ENABLE_CLUSTER_MONITORING='${ENABLE_CLUSTER_MONITORING:-false}'"