update radiogroup css

components/radio/group.jsx

@@ -4,7 +4,7 @@ var Radio = require('rc-radio');
 var AntRadioGroup = React.createClass({
   getDefaultProps: function () {
     return {
-      prefixCls: 'rc-radio-group'
+      prefixCls: 'ant-radio-group'
     };
   },
   getInitialState: function () {

style/components/radio.less

-@radioGroupPrefixCls: rc-radio-group;
+@radioGroupPrefixCls: ant-radio-group;
 @radioWrapPrefixCls: ant-radio;
 @radioInnerPrefixCls: ~"@{radioWrapPrefixCls}-inner";
 @radioDuration: .3s;