updated assemble.io dependencies so it can run on more modern NPM implementations

package.json

@@ -1,10 +1,15 @@
 {
   "dependencies": {
-    "assemble": "~0.4.0",
-    "grunt": "~0.4.1",
+    "assemble": "^0.4.42",
+    "grunt": "^0.4.5",
+    "grunt-contrib-clean": "^0.6.0",
     "grunt-contrib-compass": "^1.0.3",
-    "grunt-sync": "^0.2.3",
-    "highlight.js": "^8.5.0",
+    "grunt-contrib-copy": "^0.7.0",
+    "grunt-contrib-watch": "^0.6.1",
+    "grunt-git": "^0.3.7",
+    "grunt-http-server": "^1.16.0",
+    "grunt-sync": "^0.2.4",
+    "highlight.js": "^8.9.1",
     "string": "^3.1.1"
   },
   "devDependencies": {