Upgrade packages

package.json

@@ -11,12 +11,12 @@
 	"devDependencies": {
 		"grunt": "~0.4.5",
 		"grunt-autoprefixer": "^3.0.3",
-		"grunt-concurrent": "~2.0.1",
-		"grunt-contrib-clean": "^0.6.0",
-		"grunt-contrib-cssmin": "~0.13.0",
+		"grunt-concurrent": "~2.1.0",
+		"grunt-contrib-clean": "^0.7.0",
+		"grunt-contrib-cssmin": "~0.14.0",
 		"grunt-contrib-jshint": "~0.11.2",
 		"grunt-contrib-sass": "^0.9.2",
-		"grunt-contrib-uglify": "~0.9.1",
+		"grunt-contrib-uglify": "~0.11.0",
 		"grunt-contrib-watch": "~0.6.1",
 		"grunt-shell-spawn": "^0.3.8",
 		"jit-grunt": "^0.9.1",