Update jshint rules. Removed es5:true, added expr:true. Update unused config from grunt-contrib-jshint plugin

Author: elmasse

.jshintrc

@@ -11,7 +11,7 @@
   "boss": true,
   "eqnull": true,
   "node": true,
-  "es5": true,
+  "expr": true,
   "predef": [
     "describe",         
     "it",               

Gruntfile.js

@@ -15,12 +15,7 @@ module.exports = function(grunt) {
         src: ['lib/**/*.js']
       },
       test: {
-        src: ['test/**/*.js'],
-        options: {
-            es5: true,
-            expr: true,
-            globals: {describe: true, it: true, expect: true, define: true, beforeEach: true, afterEach: true}
-        }
+        src: ['test/**/*.js']
       }
     },