WordPress example major update.

Rewrite the WordPress example to use deployments, persistent volume
claims, and update the sample flow to the latest guidelines.

examples/mysql-wordpress-pd/mysql-deployment.yaml

@@ -0,0 +1,63 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: wordpress-mysql
+  labels:
+    app: wordpress
+spec:
+  ports:
+    - port: 3306
+  selector:
+    app: wordpress
+    tier: mysql
+  clusterIP: None
+---
+apiVersion: v1
+kind: PersistentVolumeClaim
+metadata:
+  name: mysql-pv-claim
+  labels:
+    app: wordpress
+spec:
+  accessModes:
+    - ReadWriteOnce
+  resources:
+    requests:
+      storage: 20Gi
+---
+apiVersion: extensions/v1beta1
+kind: Deployment
+metadata:
+  name: wordpress-mysql
+  labels:
+    app: wordpress
+spec:
+  strategy:
+    type: Recreate
+  template:
+    metadata:
+      labels:
+        app: wordpress
+        tier: mysql
+    spec:
+      containers:
+      - image: mysql:5.6
+        name: mysql
+        env:
+          # $ kubectl create secret generic mysql-pass --from-file=password.txt
+          # make sure password.txt does not have a trailing newline
+        - name: MYSQL_ROOT_PASSWORD
+          valueFrom:
+            secretKeyRef:
+              name: mysql-pass
+              key: password.txt
+        ports:
+        - containerPort: 3306
+          name: mysql
+        volumeMounts:
+        - name: mysql-persistent-storage
+          mountPath: /var/lib/mysql
+      volumes:
+      - name: mysql-persistent-storage
+        persistentVolumeClaim:
+          claimName: mysql-pv-claim