Remove manifest copies from Trusty support

This change revises the way to provide kube-system manifests for clusters on Trusty. Originally, we maintained copies of some manifests under cluster/gce/trusty/kube-manifests, which is not scalable and hard to maintain. With this change, clusters on Trusty will use the same source of manifests as ContainerVM. This change also fixes some minor problems such as shell variables and comments to meet the style guidance better.

hack/verify-flags/exceptions.txt

@@ -13,6 +13,7 @@ cluster/gce/configure-vm.sh:  cloud_config: ${CLOUD_CONFIG}
 cluster/gce/configure-vm.sh:  env-to-grains "runtime_config"
 cluster/gce/configure-vm.sh:  kubelet_api_servers: '${KUBELET_APISERVER}'
 cluster/gce/coreos/helper.sh:# cloud_config yaml file should be passed
+cluster/gce/trusty/configure.sh:  sed -i -e "s@{{pillar\['allow_privileged'\]}}@true@g" "${src_file}"
 cluster/gce/util.sh:    local node_ip=$(gcloud compute instances describe --project "${PROJECT}" --zone "${ZONE}" \
 cluster/juju/charms/trusty/kubernetes-master/files/controller-manager.upstart.tmpl:     --address=%(bind_address)s \
 cluster/juju/charms/trusty/kubernetes-master/files/scheduler.upstart.tmpl:     --address=%(bind_address)s \