[Touchable] Add custom delay props to Touchable components

Summary:
@public
This PR adds quite a bit of functionality to the Touchable components, allowing the ms delays of each of the handlers (`onPressIn, onPressOut, onPress, onLongPress`) to be configured.

It adds the following props to `TouchableWithoutFeedback, TouchableOpacity, and TouchableHighlight`:
```javascript
/**
 * Delay in ms, from the release of the touch, before onPress is called.
 */
delayOnPress: React.PropTypes.number,
/**
 * Delay in ms, from the start of the touch, before onPressIn is called.
 */
delayOnPressIn: React.PropTypes.number,
/**
 * Delay in ms, from the release of the touch, before onPressOut is called.
 */
delayOnPressOut: React.PropTypes.number,
/**
 * Delay in ms, from onPressIn, before onLongPress is called.
 */
delayOnLongPress: React.PropTypes.number,
```

`TouchableHighlight` also gets an additional set of props:
```javascript
/**
 * Delay in ms, from the start of the touch, before the highlight is shown.
 */
delayHighlightShow: React.PropTypes.number,
/**
 * Del
...
```

Closes https://github.com/facebook/react-native/pull/1255
Github Author: jmstout <git@jmstout.com>

Test Plan: Imported from GitHub, without a `Test Plan:` line.

Examples/UIExplorer/TouchableExample.js

@@ -75,6 +75,14 @@ exports.examples = [
   render: function(): ReactElement {
     return <TouchableFeedbackEvents />;
   },
+}, {
+  title: 'Touchable delay for events',
+  description: '<Touchable*> components also accept delayPressIn, ' +
+    'delayPressOut, and delayLongPress as props. These props impact the ' +
+    'timing of feedback events.',
+  render: function(): ReactElement {
+    return <TouchableDelayEvents />;
+  },
 }];
 
 var TextOnPressBox = React.createClass({
@@ -148,6 +156,44 @@ var TouchableFeedbackEvents = React.createClass({
   },
 });
 
+var TouchableDelayEvents = React.createClass({
+  getInitialState: function() {
+    return {
+      eventLog: [],
+    };
+  },
+  render: function() {
+    return (
+      <View>
+        <View style={[styles.row, {justifyContent: 'center'}]}>
+        <TouchableOpacity
+          style={styles.wrapper}
+          onPress={() => this._appendEvent('press')}
+          delayPressIn={400}
+          onPressIn={() => this._appendEvent('pressIn - 400ms delay')}
+          delayPressOut={1000}
+          onPressOut={() => this._appendEvent('pressOut - 1000ms delay')}
+          delayLongPress={800}
+          onLongPress={() => this._appendEvent('longPress - 800ms delay')}>
+          <Text style={styles.button}>
+            Press Me
+          </Text>
+        </TouchableOpacity>
+      </View>
+        <View style={styles.eventLogBox}>
+          {this.state.eventLog.map((e, ii) => <Text key={ii}>{e}</Text>)}
+        </View>
+      </View>
+    );
+  },
+  _appendEvent: function(eventName) {
+    var limit = 6;
+    var eventLog = this.state.eventLog.slice(0, limit - 1);
+    eventLog.unshift(eventName);
+    this.setState({eventLog});
+  },
+});
+
 var heartImage = {uri: 'https://pbs.twimg.com/media/BlXBfT3CQAA6cVZ.png:small'};
 
 var styles = StyleSheet.create({