MAS-253 Update usage of depracated tinymce methods

Author: emollett

cms/public/js/accreditation.js

@@ -1,9 +1,9 @@
 window.tinymce.PluginManager.add("accreditation", function(editor) {
 	// Add a button that inserts the accreditation image withing an img tag.
-	editor.addButton("accreditation", {
+	editor.ui.registry.addButton("accreditation", {
 		tooltip: "Insert accreditation image",
-		icon: "icon-accreditation",
-		onclick: function() {
+		icon: "template",
+		onAction: function() {
 			editor.insertContent(
 				'<img style="display: inline-block;" src="https://www.medicinesresources.nhs.uk/nhs_accreditation.jpg" alt="nhs accreditation logo" width="20" height="20" />'
 			);