Update molecule configuration to work with 3.0.

.yamllint

@@ -0,0 +1,6 @@
+---
+extends: default
+rules:
+  line-length:
+    max: 120
+    level: warning

molecule/default/converge.yml

@@ -0,0 +1,27 @@
+---
+- name: Converge
+  hosts: all
+  become: true
+
+  vars:
+    certbot_auto_renew_user: root
+
+  pre_tasks:
+    - name: Update apt cache.
+      apt: update_cache=yes cache_valid_time=600
+      when: ansible_os_family == 'Debian'
+      changed_when: false
+
+    - name: Install dependencies (RedHat).
+      yum: name={{ item }} state=present
+      when: ansible_os_family == 'RedHat'
+      with_items:
+        - cronie
+        - epel-release
+
+    - name: Install cron (Debian).
+      apt: name=cron state=present
+      when: ansible_os_family == 'Debian'
+
+  roles:
+    - geerlingguy.certbot