[Touch] Suite of touchable events on TouchableHighlight/Opacity

Summary:
The following props are now supported on TouchableHighlight/Opacity components:

 - onPress (was there before)
 - onPressIn
 - onPressOut
 - onLongPress

There is a `TouchableFeedbackPropType` that is shared amongst the Touchable family for consistency.

Added UIExplorer example to demonstrate and test.

Fixes #101.
Closes https://github.com/facebook/react-native/pull/102
Github Author: James Ide <ide@jameside.com>

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

Libraries/Components/Touchable/TouchableHighlight.js

@@ -11,6 +11,7 @@ var ReactIOSViewAttributes = require('ReactIOSViewAttributes');
 var StyleSheet = require('StyleSheet');
 var TimerMixin = require('TimerMixin');
 var Touchable = require('Touchable');
+var TouchableFeedbackPropType = require('TouchableFeedbackPropType');
 var View = require('View');
 
 var cloneWithProps = require('cloneWithProps');
@@ -50,6 +51,7 @@ var DEFAULT_PROPS = {
 
 var TouchableHighlight = React.createClass({
   propTypes: {
+    ...TouchableFeedbackPropType,
     /**
      * Called when the touch is released, but not if cancelled (e.g. by
      * a scroll that steals the responder lock).
@@ -127,12 +129,14 @@ var TouchableHighlight = React.createClass({
     this.clearTimeout(this._hideTimeout);
     this._hideTimeout = null;
     this._showUnderlay();
+    this.props.onPressIn && this.props.onPressIn();
   },
 
   touchableHandleActivePressOut: function() {
     if (!this._hideTimeout) {
       this._hideUnderlay();
     }
+    this.props.onPressOut && this.props.onPressOut();
   },
 
   touchableHandlePress: function() {
@@ -142,6 +146,10 @@ var TouchableHighlight = React.createClass({
     this.props.onPress && this.props.onPress();
   },
 
+  touchableHandleLongPress: function() {
+    this.props.onLongPress && this.props.onLongPress();
+  },
+
   touchableGetPressRectOffset: function() {
     return PRESS_RECT_OFFSET;   // Always make sure to predeclare a constant!
   },