Add tabPostion bottom

components/tabs/demo/position.md

@@ -0,0 +1,45 @@
+# 位置
+
+- order: 6
+
+有四个位置，`tabPosition="left|right|top|bottom"`。
+
+---
+
+````jsx
+import { Tabs, Select } from 'antd';
+const TabPane = Tabs.TabPane;
+const Option = Select.Option;
+
+const Demo = React.createClass({
+  getInitialState() {
+    return {
+      tabPosition: 'top',
+    };
+  },
+  changeTabPosition(tabPosition) {
+    this.setState({ tabPosition });
+  },
+  render() {
+    return <div>
+      <div style={{marginBottom: 16}}>
+        页签位置：
+        <Select value={this.state.tabPosition} onChange={this.changeTabPosition}
+          dropdownMatchSelectWidth={false}>
+          <Option value="top">top</Option>
+          <Option value="bottom">bottom</Option>
+          <Option value="left">left</Option>
+          <Option value="right">right</Option>
+        </Select>
+      </div>
+      <Tabs tabPosition={this.state.tabPosition}>
+        <TabPane tab="选项卡一" key="1">选项卡一内容</TabPane>
+        <TabPane tab="选项卡二" key="2">选项卡二内容</TabPane>
+        <TabPane tab="选项卡三" key="3">选项卡三内容</TabPane>
+      </Tabs>
+    </div>;
+  }
+});
+
+ReactDOM.render(<Demo />, document.getElementById('components-tabs-demo-position'));
+````

style/components/tabs.less

@@ -364,6 +364,11 @@
     }
   }
 
+  &-bottom &-tabs-bar {
+    margin-bottom: 0;
+    margin-top: 16px;
+  }
+
 
   // card style
   &&-card &-ink-bar {