add jshint configuration

.jshintrc

+{
+	"browser": true,
+	"esversion": 6
+}

src/js/DefaultRules.tw

 :: DefaultRules [script]
-// jshint esversion: 6
-// jshint browser: true
 // this code applies RA rules onto slaves
 
 window.DefaultRules = (function() {

src/js/rulesAssistantOptions.tw

 :: Rules Assistant Options [script]
-// jshint esversion: 6
-// jshint browser: true
 // rewrite of the rules assistant options page in javascript
 // uses an object-oriented widget pattern
 // wrapped in a closure so as not to polute the global namespace