Demo code review (shared)

This is a simple pull request on a clone of a random repo, so you can play with Reviewable a bit.  It's not complex enough to demo all the features but it'll get you started.  Note that it's shared between all visitors to the site, so if things get a bit too rowdy we may reset the state the review's state every so often.

You play the role of a reviewer.  Some things to try:
- Expand a collapsed section of a file, up or down.
- Select a different diff range by dragging out a range in a revision table (clicking also works).
- Select a different diff range for all files by dragging on the header of the main file matrix above this discussion.  Expand the legend to understand the various icons used.
- Jump to an unreplied comment by clicking on "to reply" (comment icon) in the status bar.  Acknowledge one, reply to another.
- Draft a comment on a line in one revision, then switch the diff range to another revision.
- Do that again, but on a line that doesn't exist in the other revision.
- Mark some file revisions as reviewed by clicking the red crossed eye button.
- Cycle through unreviewed files by clicking on "to review" (crossed eye icon) in the status bar.
- Drop down the overlay by clicking on the bunny icon in the status bar, then jump to another file or edit your top-level discussion draft.
- Cycle through your drafts by clicking on "drafts" (pencil icon) in the status bar.
- Complete a review cycle by clicking the Publish button in the status bar.

In a real review, it would now be up to the reviewee to fix the code and reply to the comments, iterating like this until all files are reviewed and all comments resolved.  Unfortunately, this is as far as the demo goes...  Try it for real on your own pull request!

BTW, when you're done, you may want to unsubscribe from the pull request so you don't get spammed when other people play with it.