message: [table] show 'Time' column header instead of '__timestamp'
diff: @@ -145,10 +145,11 @@ class BaseDatasource(AuditMixinNullable, ImportMixin):
  order_by_choices.append((json.dumps([s, True]), s + ' [asc]'))
  order_by_choices.append((json.dumps([s, False]), s + ' [desc]'))
  - verbose_map = {
  + verbose_map = {'__timestamp': 'Time'}
  + verbose_map.update({
  o.metric_name: o.verbose_name or o.metric_name
  for o in self.metrics
  - }
  + })
  verbose_map.update({
  o.column_name: o.verbose_name or o.column_name
  for o in self.columns
  