chore(package): Update node-zopfli version

Author: robertbachmann

package.json

@@ -1,14 +1,14 @@
 {
   "name": "compression-webpack-plugin",
-  "version": "0.3.1",
+  "version": "0.3.2",
   "author": "Tobias Koppers @sokra",
   "description": "Prepare compressed versions of assets to serve them with Content-Encoding",
   "dependencies": {
     "async": "0.2.x",
     "webpack-sources": "^0.1.0"
   },
   "optionalDependencies": {
-    "node-zopfli": "^1.3.4"
+    "node-zopfli": "^2.0.0"
   },
   "homepage": "http://github.com/webpack/compression-webpack-plugin",
   "repository": {