Since Xtab UI creates the binding with correct aggregate function, Chart
UI will reuse this binding as y value when creating chart view.
Count on date should set y axis type as numerical.
Also fixed two new issues in xtab UI:
1. If measure's data type is date, aggregation function should be Count,
and data type should change to integer.
2. If there are same measure name in other cubes, should not get the
reference from there.