Fix incorrect file existence check and fix npm test

[bugron]

Not sure why is this commit b39fd1f merged into the branch stable because Node will check for existence of a directory with name config instead of config.js, so it won't add .js extension for you obviously.
Next thing this commit fixes is npm test. First cause it is failing is the issue above. Not sure what's the second one but after I've added test/*.js, npm test stopped failing.

[askmike]

thanks!