Migration to Heroku

This release migrates most of the logic to Heroku, and in doing so enables asynchronous code. This unlocks significant performance benefits, hopefully making timeout errors a thing of the past.

Other minor changes: handle get requests, show user name when mousing over avatar

1.1.0: Improve handling of offsets

This release creates a ColumnLocator ADT which much more cleanly represents offsets, and generally makes spreadsheet accesses cleaner.

Initial release

Initial release: /in, /out, /h, /announce, and announce message.