Updates to the JVM charting code

Removed chart and CSV file generation from ReportJVMMonitorStage. It now
calls LocalSystemMonitorChart instead.

Update constant name used in Start|StopJVMMonitorStage.

Update the chart and CSV file generation code in
LocalSystemMonitorChart.

Remove the data calibration from
AbstractActivityMonitor.formatForGraph().
Generate TimeSeries charts from AbstractActivityMonitor measurements

ClusterTimeSeriesReport - new class to hold TimeSeries data from
individual AbstractActivityMonitor objects.
TimeSeriesReportGenerator - new class to generate the chart from a
ClusterTimeSeriesReport object
LocalSystemMonitorChart - modified to use ClusterTimeSeriesReport
objects, instead of ClusterReport objects
AbstractActivityMonitor, CpuUsageMonitor, GcMonitor, MemoryUsageMonitor
- add support for getting the time when the first measurement in the
monitor was taken
LocalJmxMonitor - Synchronize the intervals when the
measurements are taken
Extract AbstractClusterReport superclass and start charts at 00:00:00
Updated the XSD to match the build after afield's changes