Fix not specifying file name with test in package.json (#289)

This makes it possible to test each file with `npm test FILE_NAME`.

Author: abetomo

package.json

@@ -7,7 +7,7 @@
     "test": "test"
   },
   "scripts": {
-    "test": "mocha test/*.js"
+    "test": "mocha"
   },
   "bin": {
     "node-lambda": "./bin/node-lambda"