Summary:
Allows developers to specify headers to include in the HTTP request
when fetching a remote image. For example, one might leverage this
when fetching an image from an endpoint that requires authentication:
```
<Image
style={styles.logo}
source={{
uri: 'http://facebook.github.io/react/img/logo_og.png',
headers: {
Authorization: 'someAuthToken'
}
}}
/>
```
Note that the header values must be strings.
Works on iOS and Android.
**Test plan (required)**
- Ran a small example like the one above on iOS and Android and ensured the headers were sent to the server.
- Ran a small example to ensure that \<Image\> components without headers still work.
- Currently using this code in our app.
Adam Comella
Microsoft Corp.
Closes https://github.com/facebook/react-native/pull/7338
Reviewed By: javache
Differential Revision: D3371458
Pulled By: nicklockwood
fbshipit-source-id: cdb24fe2572c3ae3ba82c86ad383af6d85157e20
ee8496f364
