Combine JavaScript & CSS files by Combo.js in Node.js.

The Combo URL Format is:
http://yourcdn.com/example/hello.js
http://yourcdn.com/example/fun.js
http://yourcdn.com/combo=example/hello.js
http://yourcdn.com/combo=example/hello.js&example/fun.js

0.1.0
1. Make sure the combo url format. Combine the files by the combo url.
2. Throw friendly error, if some file isn't exist. Return error info, so the developer will know it at once.
3. Set HTTP Header Cache Time 10 years.  

0.2.0
1. Cache exist files.
2. Hide the favicon.ico.

0.3.0
Think about 304.
...

1.0.0
run online.