change linter config for browser/node switching

Gruntfile.coffee

@@ -23,8 +23,14 @@ module.exports = (grunt) ->
         src: ['test/**/*.js']
 
     jshint:
-      all: ['bin/embark', 'lib/**/*.js', 'js/mine.js', 'js/embark.js'],
+      all: ['bin/embark', 'lib/**/*.js']
       options: grunt.file.readJSON('package.json').jshintConfig
+      with_overrides:
+        options:
+          undef: false
+          esversion: 5
+        files:
+          src: ['js/mine.js', 'js/embark.js']
 
   grunt.loadTasks "tasks"
   require('matchdep').filterAll(['grunt-*','!grunt-cli']).forEach(grunt.loadNpmTasks)

package.json

@@ -67,11 +67,13 @@
     "white": true,
     "node": true,
     "undef": true,
-    "unused": true,
     "-W058": true,
     "-W014": true,
     "expr": true,
     "esversion": 6,
-    "unused": false
+    "unused": false,
+    "globals": {
+      "node": true
+    }
   }
 }