add test and update API call + domain structure

I just added test and also update the the API call and domain data structure which is outdated.
It's unpredictable that 429 error comes up sometimes which maybe related to these discussion below:
http://stackoverflow.com/questions/8963485/error-429-when-invoking-reddit-api-from-google-app-engine
https://github.com/reddit/reddit/wiki/API