Refactor Chart component into generic superclass

Refactor the workflow specific EventHistoryChart into a generalized superclass, e.g. TimeseriesChart, that will be extended within the scope of each workflow.

Provide API to support:

• setting the chart title
• title for axis are extracted from timeseries object, providing the corresponding header information
• provide setter for timeseries data, e.g. setTimeseries(timeseries, left/right, bar/line, color)

The similarity workflow specific parts should be covered by a corresponding child class (e.g. GaugeTimeseriesChart), extracting the timeseries data for a particular gauge.