Remove imagemin version restriction.

 {
   "name": "grunt-monty-python",
-  "version": "2016.05.24-0",
+  "version": "2016.05.24-1",
   "description": "Build system for grunt",
   "license": "BSD",
   "repository": {
@@ -23,7 +23,7 @@
     "grunt-contrib-cssmin": "~0.12.3",
     "grunt-contrib-jshint": "~0",
     "grunt-contrib-htmlmin": "~0",
-    "grunt-contrib-imagemin": "~0",
+    "grunt-contrib-imagemin": "",
     "grunt-contrib-jasmine": "",
     "grunt-contrib-requirejs": "~0",
     "grunt-contrib-uglify": "~0",