Feature: Added automagical coin switching based on profitability

Configurable.  Updated example config to include setting defaulted to off.  Added "host" parameter to the coinSwitchListener config so we send our switch messages to the right place.

Things that would be cool to add:

Pull in Bitcoinaverage.com API information and allow config of local currency to use for profitability calculation and display - would enable a  USD $0.10 per MH per hour display or some such.

Graphs: Like difficulty, profitability history, coin switches, etc.  Shouldn't be too hard to do.