Add PodTemplateGroup#addTemplate (#1520)

Author: Dohbedoh

src/main/java/org/csanchez/jenkins/plugins/kubernetes/KubernetesCloud.java

@@ -703,6 +703,7 @@ public List<PodTemplate> getTemplatesFor(@CheckForNull Label label) {
      * Add a new template to the cloud
      * @param t docker template
      */
+    @Override
     public void addTemplate(PodTemplate t) {
         this.templates.add(t);
         // t.parent = this;

src/main/java/org/csanchez/jenkins/plugins/kubernetes/PodTemplateGroup.java

@@ -3,6 +3,13 @@
  * A group of pod templates that can be saved together.
  */
 public interface PodTemplateGroup {
+
+    /**
+     * Add the template to the group.
+     * @param podTemplate the template to add
+     */
+    void addTemplate(PodTemplate podTemplate);
+
     /**
      * Replaces the old template with the new template.
      * @param oldTemplate the old template to replace