Update Grunt peer dependency to support 1.0.0

Author: stephenharris

package.json

@@ -44,7 +44,7 @@
     "grunt-contrib-jshint": "0.11.x"
   },
   "peerDependencies": {
-    "grunt": "0.4.x"
+    "grunt": ">=0.4.0"
   },
   "keywords": [
     "gruntplugin",