feat(ZFSPV): adding encryption in ZFSVolume CR (#6)

Adding support for enabling encryption using a custom key. 

Also, adding support to inherit the properties from ZPOOL
which are not listed in the storage class, ZFS driver will
not pass default values while creating the volume. Those
properties will be inherited from the ZPOOL.

we can use the encryption option in storage class 
```
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: openebs-zfspv
allowVolumeExpansion: true
parameters:
  blocksize: "4k"
  compression: "on"
  dedup: "on"
  thinprovision: "yes"
  encryption: "on"
  keyformat: "raw"
  keylocation: "file:///home/keys/key"
  poolname: "zfspv-pool"
provisioner: openebs.io/zfs
```

Just a note, the key file should be mounted inside the node-agent container so that we can use that file while provisioning the volume. keyformat can be raw, hex or passphrase.

Signed-off-by: Pawan <pawan@mayadata.io>

deploy/sample/percona.yaml

@@ -0,0 +1,131 @@
+apiVersion: storage.k8s.io/v1
+kind: StorageClass
+metadata:
+  name: openebs-zfspv
+allowVolumeExpansion: true
+parameters:
+  blocksize: "4k"
+  compression: "on"
+  dedup: "on"
+  thinprovision: "yes"
+  poolname: "zfspv-pool"
+provisioner: openebs.io/zfs
+---
+kind: PersistentVolumeClaim
+apiVersion: v1
+metadata:
+  name: csi-zfspv
+spec:
+  storageClassName: openebs-zfspv
+  accessModes:
+    - ReadWriteOnce
+  resources:
+    requests:
+      storage: 4Gi
+---
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  annotations:
+  name: sqltest
+  namespace: default
+data:
+  sql-test.sh: |
+    #!/bin/bash
+
+    DB_PREFIX="Inventory"
+    DB_SUFFIX=`echo $(mktemp) | cut -d '.' -f 2`
+    DB_NAME="${DB_PREFIX}_${DB_SUFFIX}"
+
+
+    echo -e "\nWaiting for mysql server to start accepting connections.."
+    retries=10;wait_retry=30
+    for i in `seq 1 $retries`; do
+      mysql -uroot -pk8sDem0 -e 'status' > /dev/null 2>&1
+      rc=$?
+      [ $rc -eq 0 ] && break
+      sleep $wait_retry
+    done
+
+    if [ $rc -ne 0 ];
+    then
+      echo -e "\nFailed to connect to db server after trying for $(($retries * $wait_retry))s, exiting\n"
+      exit 1
+    fi
+    mysql -uroot -pk8sDem0 -e "CREATE DATABASE $DB_NAME;"
+    mysql -uroot -pk8sDem0 -e "CREATE TABLE Hardware (id INTEGER, name VARCHAR(20), owner VARCHAR(20),description VARCHAR(20));" $DB_NAME
+    mysql -uroot -pk8sDem0 -e "INSERT INTO Hardware (id, name, owner, description) values (1, "dellserver", "basavaraj", "controller");" $DB_NAME
+    mysql -uroot -pk8sDem0 -e "DROP DATABASE $DB_NAME;"
+---
+apiVersion: apps/v1beta1
+kind: Deployment
+metadata:
+  name: percona
+  labels:
+    name: percona
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      name: percona
+  template:
+    metadata:
+      labels:
+        name: percona
+    spec:
+      affinity:
+        nodeAffinity:
+          requiredDuringSchedulingIgnoredDuringExecution:
+            nodeSelectorTerms:
+            - matchExpressions:
+              - key: kubernetes.io/hostname
+                operator: In
+                values:
+                - gke-pawan-zfspv-default-pool-26f2b9a9-5fqd
+      containers:
+        - resources:
+          name: percona
+          image: openebs/tests-custom-percona:latest
+          imagePullPolicy: IfNotPresent
+          args:
+            - "--ignore-db-dir"
+            - "lost+found"
+          env:
+            - name: MYSQL_ROOT_PASSWORD
+              value: k8sDem0
+          ports:
+            - containerPort: 3306
+              name: percona
+          volumeMounts:
+            - mountPath: /var/lib/mysql
+              name: demo-vol1
+            - mountPath: /sql-test.sh
+              subPath: sql-test.sh
+              name: sqltest-configmap
+          livenessProbe:
+            exec:
+              command: ["bash", "sql-test.sh"]
+            initialDelaySeconds: 30
+            periodSeconds: 1
+            timeoutSeconds: 10
+      volumes:
+        - name: demo-vol1
+          persistentVolumeClaim:
+            claimName: csi-zfspv
+        - name: sqltest-configmap
+          configMap:
+            name: sqltest
+
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: percona-mysql
+  labels:
+    name: percona-mysql
+spec:
+  ports:
+    - port: 3306
+      targetPort: 3306
+  selector:
+      name: percona