Switch to using a Stateful Set, which is for stateful applications

There doesn't seem to be any tangible difference in the performance between
using a Deployment or a StatefulSet but the docs say it's for stateful apps.

k8s/jenkins.yaml.template

@@ -10,19 +10,6 @@ items:
     metadata:
       name: "jenkins-@@USER@@"
 
-  - apiVersion: v1
-    kind: PersistentVolumeClaim
-    metadata:
-      name: "jenkins-@@USER@@"
-      namespace: "jenkins-@@USER@@"
-    spec:
-      storageClassName: azurefile
-      accessModes:
-        - ReadWriteMany
-      resources:
-        requests:
-          storage: 5Gi
-
   - apiVersion: v1
     kind: Service
     metadata:
@@ -63,18 +50,29 @@ items:
               serviceName: 'jenkins-@@USER@@'
               servicePort: 80
 
-  - apiVersion: extensions/v1beta1
-    kind: Deployment
+  - apiVersion: apps/v1beta1
+    kind: StatefulSet
     metadata:
       name: "jenkins-@@USER@@"
       namespace: "jenkins-@@USER@@"
       labels:
         name: "jenkins-@@USER@@"
     spec:
+      serviceName: 'jenkins-@@USER@@'
       replicas: 1
-      strategy:
-        type: RollingUpdate
       selector:
+        matchLabels:
+          app: 'jenkins-@@USER@@'
+      volumeClaimTemplates:
+        - metadata:
+            name: "jenkins-@@USER@@"
+            namespace: "jenkins-@@USER@@"
+          spec:
+            accessModes:
+              - ReadWriteOnce
+            resources:
+              requests:
+                storage: 5Gi
       template:
         metadata:
           labels:
@@ -85,10 +83,6 @@ items:
             fsGroup: 1000
             # https://github.com/kubernetes/kubernetes/issues/2630#issuecomment-344091454
             runAsUser: 0
-          volumes:
-            - name: "jenkins-@@USER@@"
-              persistentVolumeClaim:
-                claimName: "jenkins-@@USER@@"
           containers:
             - name: "jenkins-@@USER@@"
               image: "rtyler/codevalet-master:latest"