Add synthetic scale deployment mode

New deploy modes: scale, ha-scale, separate-scale
Creates 200 fake hosts for deployment with fake hostvars.

Useful for testing certificate generation and propagation to other
master nodes.

Updated test cases descriptions.

roles/etcd/tasks/check_certs.yml

@@ -2,6 +2,7 @@
 - name: "Check_certs | check if all certs have already been generated on first master"
   stat:
     path: "{{ etcd_cert_dir }}/{{ item }}"
+    get_md5: no
   delegate_to: "{{groups['etcd'][0]}}"
   register: etcdcert_master
   run_once: true