Update molecule configuration to work with 3.0.

Author: geerlingguy

.yamllint

@@ -0,0 +1,6 @@
+---
+extends: default
+rules:
+  line-length:
+    max: 160
+    level: warning

molecule/default/converge.yml

@@ -0,0 +1,16 @@
+---
+- name: Converge
+  hosts: all
+  become: true
+
+  roles:
+    - role: geerlingguy.mysql
+
+  post_tasks:
+    - name: Make sure we can connect to MySQL via Unix socket.
+      command: "mysql -u root -proot -e 'show databases;'"
+      changed_when: false
+
+    - name: Make sure we can connect to MySQL via TCP.
+      command: "mysql -u root -proot -h 127.0.0.1 -e 'show databases;'"
+      changed_when: false