docker: remove checks for docker 1.12

Signed-off-by: Etienne Champetier <champetier.etienne@gmail.com>

roles/container-engine/docker/tasks/main.yml

@@ -213,14 +213,6 @@
   changed_when: false
   check_mode: false
 
-- name: check minimum docker version for docker_dns mode. You need at least docker version >= 1.12 for resolvconf_mode=docker_dns
-  fail:
-    msg: "You need at least docker version >= 1.12 for resolvconf_mode=docker_dns"
-  when: >
-        dns_mode != 'none' and
-        resolvconf_mode == 'docker_dns' and
-        installed_docker_version.stdout is version('1.12', '<')
-
 # Install each plugin using a looped include to make error handling in the included task simpler.
 - include_tasks: docker_plugin.yml
   loop: "{{ docker_plugins }}"