[Android] Use native Share Dialog


Use Native Share Dialog and fallback to Feeds Dialog when it is not available (as recommended by Facebook: https://developers.facebook.com/docs/android/share#linkfeed)

Related to issue: #681
I think as this is JavaScript, and the JavaScript API takes `href` (see https://developers.facebook.com/docs/javascript/reference/FB.ui)
The correct first input should be `href`, but keep link in the options for native to pickup. How do you think?

```
// link is for the native shareDialog API
link: options.href,
// href is for the JS SDK
href: options.href,
```