Base framework for http://skia-tree-status.appspot.com.

Some of the code here was copied and significantly modified to only include
logic for statuses from
http://src.chromium.org/viewvc/chrome/trunk/tools/chromium-status/

Upload the web app to AppEngine with the following steps:
1) Install the Python AppEngine SDK
2) Ensure your local checkout is clean and run `make upload`
3) Go to https://appengine.google.com/deployment?app_id=s~skia-tree-status
4) Test your new version by clicking on it. If everything works make it the new
   default