Set min/max properly in histogram converter

[spalger]

When an indexPattern is not time-based, the chart.ordered.min and chart.ordered.max as still being set using the timefilter. This fixes that by reading the data in that case.

[rashidkpc]

+        if (captureXRange) {
+          chart.ordered.min = chart.ordered.min === void 0 ? datum.x : Math.min(chart.ordered.min, datum.x);
+          chart.ordered.max = chart.ordered.max === void 0 ? datum.x : Math.max(chart.ordered.max, datum.x);
+        }

This is calculating min/max when it isn't passed. We shouldn't need to pass min/max at all, the vislib should be able to calculate these values.

[spalger]

@stormpython @jthomassie Can one of you guys take a look at my vislib changes?

[jthomassie]

@spenceralger looks good to me