add ios orientations support

[aizigao]

On iOS, the modal is still restricted by what's specified in your app's Info.plist's UISupportedInterfaceOrientations field. react native doc modal, so need add flowing code to support supportedOrientations,

<Modal
        visible={true}
        supportedOrientations={['portrait', 'landscape']}  // 使ios上支持横屏显示
>
</Modal>

see issue

[coveralls]

Changes Unknown when pulling f10a2ab on aizigao:master into ** on react-component:master**.

[aizigao]

native ios 上现在不能横屏显示弹窗

[silentcloud]

@paranoidjk 发个版本

[silentcloud]

ant-design/ant-design-mobile#1704

[paranoidjk]

@silentcloud + silentcloud (rc-dialog) done