Add optional deployment mode for Docker etcd_deployment_type

Running etcd in Docker reduces the number of individual file
downloads and services running on the host.

Note: etcd container v3.0.1 moves bindir to /usr/local/bin

Fixes: #298

roles/etcd/tasks/configure.yml

@@ -12,7 +12,7 @@
 
 - name: Configure | Copy etcd.service systemd file
   template:
-    src: etcd.service.j2
+    src: "etcd-{{ etcd_deployment_type }}.service.j2"
     dest: /etc/systemd/system/etcd.service
     backup: yes
   when: ansible_service_mgr == "systemd"
@@ -20,7 +20,7 @@
 
 - name: Configure | Write etcd initd script
   template:
-    src: deb-etcd.initd.j2
+    src: "deb-etcd-{{ etcd_deployment_type }}.initd.j2"
     dest: /etc/init.d/etcd
     owner: root
     mode: 0755