1. Add rowKey prop for Table.
2. Add clearSelection method for Table.
2. Add reserveSelection prop for TableColumn[type="selection"]

* fix align

* fix input number min max

Test/component/input

fix textarea autosize bug

DatePicker: fix input style in IE, fixed #498

1. Add TableStore & TableLayout.
2. Remove customCriteria & customBackgroundColors.
3. Remove fixedColumnCount.
4. Add fixed prop for TableColumn.
5. Add selectable prop for TableColumn[type="selection"].

VuePopper: add test

DatePicker: add test

DatePicker: clean code

DatePicker: fix panel style, #318

Improve Tree

Steps: add vertical-align: middle

alert.css should use variables for colours instead of hardcoded values

1. Add props: renderContent, highlightCurrent
2. Fix Bug: tree do not change when data changed