Delete: unused controller
Fix: dataSource controller bug
Mod: dataSource tree
Delete: unused log
Add: drag function in dataSource tree
Mod: database for multi datasources
Mod: logicals, controllers and relevant test
Mod: aggregation and Filter interactive page
Mod: html and style for filter && aggregation
Add: aggregation for Widget Number
Fix: Widget Donut bug

Bug: display nothing bug when value is 0
Delete: delete unused variables
Merge pull request #55 from slycloud/master

Add: dataSource tree && aggregation operation for Widget Number, Donut