Add webpack as devDependency

Fix #10

Author: Nicolas Gallagher

package.json

@@ -13,7 +13,8 @@
 	"devDependencies": {
 		"file-loader": "*",
 		"style-loader": "*",
-		"css-loader": "*"
+		"css-loader": "*",
+		"webpack": "*"
 	},
 	"homepage": "http://github.com/webpack/extract-text-webpack-plugin",
 	"repository": {
@@ -26,4 +27,4 @@
 			"url": "http://www.opensource.org/licenses/mit-license.php"
 		}
 	]
-}
+}