Add TextTrackType export and textTracks prop

Video.js

@@ -2,6 +2,7 @@ import React, {Component} from 'react';
 import PropTypes from 'prop-types';
 import {StyleSheet, requireNativeComponent, NativeModules, View, ViewPropTypes, Image} from 'react-native';
 import resolveAssetSource from 'react-native/Libraries/Image/resolveAssetSource';
+import TextTrackType from './TextTrackType';
 import VideoResizeMode from './VideoResizeMode.js';
 
 const styles = StyleSheet.create({
@@ -10,6 +11,8 @@ const styles = StyleSheet.create({
   },
 });
 
+export { TextTrackType };
+
 export default class Video extends Component {
 
   constructor(props) {
@@ -282,6 +285,18 @@ Video.propTypes = {
       PropTypes.number
     ])
   }),
+  textTracks: PropTypes.arrayOf(
+    PropTypes.shape({
+      title: PropTypes.string,
+      uri: PropTypes.string.isRequired,
+      type: PropTypes.oneOf([
+        TextTrackType.SRT,
+        TextTrackType.TTML,
+        TextTrackType.VTT,
+      ]),
+      language: PropTypes.string.isRequired
+    })
+  ),
   paused: PropTypes.bool,
   muted: PropTypes.bool,
   volume: PropTypes.number,