Add flag to node e2e test specifying location of ssh privkey

hack/verify-flags/exceptions.txt

@@ -36,6 +36,7 @@ cluster/photon-controller/templates/salt-minion.sh:  hostname_override: $(ip rou
 cluster/photon-controller/util.sh:    node_ip=$(${PHOTON} vm networks "${node_id}" | grep -i $'\t'"00:0C:29" | grep -E '[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+' | head -1 | awk -F'\t' '{print $3}')
 cluster/photon-controller/util.sh:  local cert_dir="/srv/kubernetes"
 cluster/photon-controller/util.sh:  node_name=${1}
+cluster/photon-controller/util.sh:  ssh_key=$(ssh-add -L | head -1)
 cluster/rackspace/util.sh:    local node_ip=$(nova show --minimal ${NODE_NAMES[$i]} \
 cluster/saltbase/salt/cluster-autoscaler/cluster-autoscaler.manifest:{% set params = pillar['autoscaler_mig_config'] + " " + cloud_config -%}
 cluster/saltbase/salt/etcd/etcd.manifest:        "value": "{{ storage_backend }}"

hack/verify-flags/known-flags.txt

@@ -573,6 +573,7 @@ sort-by
 source-file
 ssh-env
 ssh-keyfile
+ssh-key
 ssh-options
 ssh-user
 start-services