Update calico-node systemd unit

New calicoctl does not support --detach=false option, so we should
use a recommended way to run calico-node service:
http://docs.projectcalico.org/v2.0/usage/configuration/as-service

Closes #674, #675

roles/network_plugin/calico/templates/calico.env.j2

@@ -0,0 +1,14 @@
+ETCD_ENDPOINTS="{{ etcd_access_endpoint }}"
+ETCD_CA_CERT_FILE="{{ calico_cert_dir }}/ca_cert.crt"
+ETCD_CERT_FILE="{{ calico_cert_dir }}/cert.crt"
+ETCD_KEY_FILE="{{ calico_cert_dir }}/key.pem"
+CALICO_IP="{{ip | default(ansible_default_ipv4.address) }}"
+CALICO_IP6=""
+{% if calico_network_backend is defined %}
+CALICO_NETWORKING_BACKEND="{{calico_network_backend }}"
+{% endif %}
+{% if inventory_hostname in groups['kube-node'] and peer_with_router|default(false)%}
+CALICO_AS="{{ local_as }}"
+{% endif %}
+CALICO_NO_DEFAULT_POOLS="true"
+CALICO_LIBNETWORK_ENABLED="true"