For Charts, Add Drag support for Time Range Selections

The ability to drag on a chart and select a date/time range and then fire an event that application can respond to with that selected range.
This should be available to: avail charts, single metric charts and multi-metric charts.

NOTE: the chart will not automatically make these data selections as the operation premise is on immutable datasets passed into the chart. The chart will react to the drag event and publish an angular event('ChartTimeRangeChanged') that the application can respond to if it chooses. Hawkular charts(the view) will never change the actual datasets(the model) that it receives.