Fix some JSHint issues

Mostly to reduce the scope of disabled warnings.

- Allow es6 syntax
- Disable specific lint rather than all where possible
- Update jshint while we're at it

.jshintrc

@@ -1,6 +1,6 @@
 {
   "eqeqeq": true,
-  "esversion": 5,
+  "esversion": 6,
   "freeze": true,
   "futurehostile": true,
   "latedef": "nofunc",

package.json

@@ -55,7 +55,7 @@
     "grunt-browserify": "^5.0.0",
     "grunt-contrib-connect": "^1.0.2",
     "grunt-contrib-copy": "^1.0.0",
-    "grunt-contrib-jshint": "^1.0.0",
+    "grunt-contrib-jshint": "^1.1.0",
     "grunt-contrib-qunit": "^1.2.0",
     "grunt-contrib-uglify": "^2.0.0",
     "grunt-contrib-watch": "^1.0.0",

src/core/loader.js

@@ -257,14 +257,14 @@ module.exports = {
             isAsset = function(a) {
                 return Crafty.asset(a) || null;
             },
-            // jshint ignore:start
+
             isSupportedAudio = function(f) {
 
                 return Crafty.support.audio && Crafty.audio.supports(
                     Utility.fileTypeOf( f ).type
                 );
             },
-            // jshint ignore:end
+
             isValidImage = function(f) {
 
                 return -1 < Crafty.imageWhitelist.indexOf(
@@ -332,7 +332,9 @@ module.exports = {
 
                     current = (typeof current === "object")  ?
                         current  :  {'': current + ''};
-                    // jshint ignore:start
+
+                    // Disable (Don't make functions in a loop) warning
+                    // jshint -W083
                     var files = Object.keys( current ).filter(function (key) {
 
                         var fileUrl = getFilePath(type, current[key]);
@@ -344,9 +346,9 @@ module.exports = {
                         )
                             return  shortURLOf( fileUrl );
                     });
+                    // jshint +W083
 
                     if ( files[0] )  obj = Crafty.audio.add(asset, files);
-                    // jshint ignore:end
                     //extract actual audio obj if audio creation was successfull
                     if ( obj )  obj = obj.obj;
 

src/core/utility.js

@@ -6,7 +6,7 @@ exports.blobOf = function blobOf(URI) {
 
     XHR.open('GET', URI);
 
-    return  new Promise(function (resolve, reject) {  // jshint ignore:line
+    return  new Promise(function (resolve, reject) {
 
         XHR.onload = function () {  resolve( this.response );  };
 

yarn.lock

@@ -1363,7 +1363,7 @@ find-up@^1.0.0:
     path-exists "^2.0.0"
     pinkie-promise "^2.0.0"
 
-[email protected], findup-sync@^0.4.3:
+[email protected]:
   version "0.4.3"
   resolved "https://registry.yarnpkg.com/findup-sync/-/findup-sync-0.4.3.tgz#40043929e7bc60adf0b7f4827c4c6e75a0deca12"
   dependencies:
@@ -1664,7 +1664,7 @@ grunt-contrib-copy@^1.0.0:
     chalk "^1.1.1"
     file-sync-cmp "^0.1.0"
 
-grunt-contrib-jshint@^1.0.0:
+grunt-contrib-jshint@^1.1.0:
   version "1.1.0"
   resolved "https://registry.yarnpkg.com/grunt-contrib-jshint/-/grunt-contrib-jshint-1.1.0.tgz#369d909b2593c40e8be79940b21340850c7939ac"
   dependencies:
@@ -3162,18 +3162,7 @@ [email protected]:
   version "0.2.0"
   resolved "https://registry.yarnpkg.com/querystring/-/querystring-0.2.0.tgz#b209849203bb25df820da756e747005878521620"
 
-qunitjs@^2.3.0:
-  version "2.3.1"
-  resolved "https://registry.yarnpkg.com/qunitjs/-/qunitjs-2.3.1.tgz#dedf1fc55c2a63c5faa3915c063a980c3facb716"
-  dependencies:
-    chokidar "1.6.1"
-    commander "2.9.0"
-    exists-stat "1.0.0"
-    findup-sync "^0.4.3"
-    js-reporters "1.2.0"
-    walk-sync "0.3.1"
-
-qunitjs@^2.4.1:
+qunitjs@^2.3.0, qunitjs@^2.4.1:
   version "2.4.1"
   resolved "https://registry.yarnpkg.com/qunitjs/-/qunitjs-2.4.1.tgz#88aba055a9e2ec3dbebfaad02471b2cb002c530b"
   dependencies: