Add support for ObjectId in shell.
Add playground app for testing scripts.
Allow hot code reloading in playground.
Remove automatic invocation of mongo.init.run on document ready.
Explicitly invoking init.run.
Try to make queries appear synchronous.

- disable shell input on request start and renable on completion.
Also hide prompt when disabling input.
Formatting.
Add api key and secret to grading url.
Remove refresh command.
Merge branch 'objectid' into playground