chore(npm): grunt-contrib-imagemin ^0.9.4 -> 1.0.0

update grunt-contrib-imagemin version to fix the error when using npm
install with Node v4.2.2

Closes #1412

Author: lvarayut

Diff for: app/templates/_package.json

@@ -45,7 +45,7 @@
     "grunt-contrib-concat": "^0.5.1",
     "grunt-contrib-copy": "^0.8.0",
     "grunt-contrib-cssmin": "^0.14.0",
-    "grunt-contrib-imagemin": "^0.9.4",
+    "grunt-contrib-imagemin": "~1.0.0",
     "grunt-contrib-jshint": "~0.11.2",
     "grunt-contrib-uglify": "^0.9.1",
     "grunt-contrib-watch": "~0.6.1",<% if (filters.jade) { %>