Prepopulate output iframe with results

Reviewed in https://codereview.appspot.com/12825047/
use project access_key for urlfetch_tree
swap project id columns for admins
allow __playground.json to specify initial files to open
__playground.json -> .playground
Hide resizers when iframed

Reviewed in https://codereview.appspot.com/12894044/
prevent assertion error in appengine_config.py
recognize cookies as well as set access key cookie query param
fix unprintable PlaygroundError
split out internal event handlers
separate out project middleware
replace run button with refresh button
move intercept app to separate file
new line at the end of HTTP error responses
Adding in expiration times for projects

Reviewed in https://codereview.appspot.com/13024048/
fix resizer bug
main page css
set expiration_seconds to be required=False
distinguish different project permission errors
new appids.py