build: fix package license

closes #15

Author: dougwilson

package.json

@@ -3,7 +3,7 @@
   "description": "cookie parsing with signatures",
   "version": "1.3.4",
   "author": "TJ Holowaychuk <tj@vision-media.ca> (http://tjholowaychuk.com)",
-  "licenses": "MIT",
+  "license": "MIT",
   "repository": "expressjs/cookie-parser",
   "keywords": [
     "cookie",