Shared Secret For Skydns

First off, please feel free to tell me if any of the code is too verbose. I tried to stick to what I though was idomatic to skydns.  

Second, I only wrote two tests for Authentication. Failure and Success. I wasn't sure if you wanted to write an auth test for every api route. If that's the case, we should probably write the tests a little different that way there's not tons of repeat code everywhere in the tests.  

I updated the readme. If it sounds confusing, please let me know and I will be more descriptive.