#1520 [HHQ-2067] adding the ability to monitor used using a percen

[Hyperic Team]

http://jira.hyperic.com/browse/HHQ-2067
It would be very very useful to be able to alert on swap used as a percentage instead of a number. Our servers have wildly different amounts of swap and we are forced to use multiple alerts when we could use just one alert if we could alert on the percentage of swap used.