chore(package): update grunt-contrib-imagemin to version 2.0.1

Closes #12

Author: greenkeeper[bot]

package.json

@@ -15,7 +15,7 @@
     "grunt-contrib-copy": "^0.7.0",
     "grunt-contrib-cssmin": "^0.12.0",
     "grunt-contrib-htmlmin": "^0.4.0",
-    "grunt-contrib-imagemin": "^0.9.2",
+    "grunt-contrib-imagemin": "^2.0.1",
     "grunt-contrib-jshint": "^0.11.0",
     "grunt-contrib-uglify": "^0.11.1",
     "grunt-contrib-watch": "^0.6.1",