+ 表格 `rowSelection` 支持多选
+ 表格可配置某行数据默认选中、不能选中。该配置对 ajax 载入的数据有效。
示例:
```
getCheckboxProps: function (value) {
    return {
        defaultValue: value.name === '胡彦祖ajax2', // 配置默认勾选的列
        disabled: value.name === '李大嘴ajax3'    // 配置无法勾选的列
    }
},
```

fix #317

Fork reqwest to https://github.com/ant-design/reqwest,
Remove xhr2 dependency cause it is useless in browser side, it will
cause some bugs in different pack solutions, waiting offcial repo resolve this problem: https://github.com/ded/reqwest/issues/204

ref: #216