Accessibility support

[Huangdongrong]

What problem does this feature solve?

组件是否考虑对ARIA的支持, 如果框架走国际路线，必须要支持 Accessibility，国外有些地区法律法规需要有Accessibility支持。

What does the proposed API look like?

Angular Material Design 的组件基本会支持Accessibility
https://material.angular.io/components/paginator/overview

[vthinkxie]

we will support SSR first, and then we will take aria into consideration.

[1166544]

@vthinkxie 现在的v1.2是否已完全支持SSR了呢？

[mikerobi]

I've started working on aria support for tabs, will probably work on menus next.

[wzhudev]

@mikerobi Feel free to make pull requests! 😆

[mikerobi]

@wendzhue I'm working on it.

Is it appropriate to add an "aria" commit type to commit-message.json?

How do you feel about warning messages if aria properties are missing? I've currently got it set up to warn in dev mode.

[mikerobi]

I'm sorry i didn't know commits to my own branch would add messages here. I will leave of the the issue id for my in progress commits.