pull changes from dev to production on 2014-04-04

This update brings these pulls, already on dev, to production:
* #761: fightball contains button specials and shouldn't be playable without them
* #751: button art for several more sets
* #764: add buttons for Japanese Beetle (unofficial) set
* #765: make chat textbox work in IE
* #750: show game ages on overview page
* #754: pages show timestamps in browser's reported timezone (API sends times in epoch seconds)
* #759: redirect to index page after logging out
* #760: autofocus on the username textbox when it's available for login