Cleanup urls
Add initial front end using React.js.
Add some basic validation.
Switch from React.js to vanilla javascript.

Plenty of time to experiment with new frameworks later. :)
Add checks for win and tie (frontend).
Prevent clicks after game ends.
Move to require.js and add dependency files.
Add gruntfile with jshint.
Add caching to tictactoe api.

Because memory is cheap and performance matters.
Update README to include run instructions.
Update README and fix bug in package.json.
Tweak README formatting.