Converted kegbot.rb to use eventmachine.

This will be useful for websockets later.
New text box that posts messages from a websocket.
The status page now receives alerts.

Everything sent to the '/alert' path will get posted to the kegbot
message on the page.
Updated README to match latest code changes.
Adding note about udpated server requirements.
Merge branch 'websocket_alerts'

This branch adds a textbox at the bottom of the status page to which
messages from kegbot are posted.

Technically anyone can post messages right now, but I might change that
later. To post a message simply send a POST to /alert with your message
in the 'msg' parameter. See sample_alert.py for an example.