address js lint warning

gui/app/utils/encoding.js

@@ -41,7 +41,7 @@ var Base64 = {
         var n, r, i;
         var s, o, u, a;
         var f = 0;
-        e = e.replace(/[^A-Za-z0-9\+\/\=]/g, "");
+        e = e.replace(/[^A-Za-z0-9+/=]/g, "");
         while (f < e.length) {
             s = this._keyStr.indexOf(e.charAt(f++));
             o = this._keyStr.indexOf(e.charAt(f++));

gui/tests/.eslintrc.js

@@ -1,5 +1,36 @@
 module.exports = {
+	root: true,
+	parserOptions: {
+		ecmaVersion: 2017,
+		sourceType: 'module'
+	},
+	extends: 'eslint:recommended',
 	env: {
+		browser: true,
+		jquery: true,
+		qunit: true,
 		embertest: true
+	},
+	rules: {
+	},
+	globals: {
+		"$": true,
+		"is": true,
+		"_": true,
+		"tinymce": true,
+		"CodeMirror": true,
+		"Drop": true,
+		"Mousetrap": true,
+		"Sortable": true,
+		"moment": true,
+		"Dropzone": true,
+		"Tooltip": true,
+		"server": true,
+		"authenticateUser": true,
+		"stubAudit": true,
+		"stubUserNotification": true,
+		"userLogin": true,
+		"Keycloak": true,
+		"slug": true
 	}
 };