Improve timer implementation

[nathanbreitsch]

The timer clears top sentences and adds to the story every two minutes. It also sends the remaining time to the client for display in the html timer div. This is bad because it requires the server to serve the message "(votetime) to vote, (submittime) to submit" every second.

The timer should be implemented using something like node-cron to schedule server side operations. There should be something like FlipClock running on the client to display remaining time. The initial connection should synchronize time on the client with time on the server.

[nathanbreitsch]

splitting this issue into two parts so evan and I can split the work.