Add Generic ExpiredLicenseException

closes elastic/elasticsearch#5

Original commit: elastic/x-pack-elasticsearch@712e40214a

src/main/java/org/elasticsearch/license/plugin/core/ExpiredLicenseException.java

@@ -0,0 +1,24 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+package org.elasticsearch.license.plugin.core;
+
+import org.elasticsearch.ElasticsearchException;
+import org.elasticsearch.rest.RestStatus;
+
+/**
+ * Exception to be thrown when a feature action requires a valid license
+ */
+public class ExpiredLicenseException extends ElasticsearchException {
+
+    public ExpiredLicenseException(String feature) {
+        super(feature + " license has expired");
+    }
+
+    @Override
+    public RestStatus status() {
+        return RestStatus.UNAUTHORIZED;
+    }
+}