Allow finish selection on Cascader parent option, close #896

components/cascader/demo/change-on-select.md

+# 选择即改变
+
+- order: 5
+
+这种交互允许只选中父级选项。
+
+---
+
+````jsx
+import { Cascader } from 'antd';
+
+const options = [{
+  value: 'zhejiang',
+  label: '浙江',
+  children: [{
+    value: 'hangzhou',
+    label: '杭州',
+    children: [{
+      value: 'xihu',
+      label: '西湖',
+    }],
+  }],
+}, {
+  value: 'jiangsu',
+  label: '江苏',
+  children: [{
+    value: 'nanjing',
+    label: '南京',
+    children: [{
+      value: 'zhonghuamen',
+      label: '中华门',
+    }],
+  }],
+}];
+
+function onChange(value) {
+  console.log(value);
+}
+
+ReactDOM.render(
+  <Cascader options={options} onChange={onChange} changeOnSelect />
+, mountNode);
+````

package.json

@@ -40,7 +40,7 @@
     "object-assign": "~4.0.1",
     "rc-animate": "~2.0.2",
     "rc-calendar": "~5.3.0",
-    "rc-cascader": "~0.7.0",
+    "rc-cascader": "~0.8.0",
     "rc-checkbox": "~1.2.0",
     "rc-collapse": "~1.4.4",
     "rc-dialog": "~5.3.1",