Add a 'working day' option

[GentlemanHal]

That allows the monitor to sleep when out of hours. For example the default working day could be set from 8am to 7pm and the monitor view would only poll between these hours.

This doesn't really provide any benefit for the end users, but it could help take a massive amount of load off the server and save some energy.

Could also blank out the screen while sleeping to stop success messages getting burnt into the screen if users forgot to turn the TV/monitor off (shame on them!)