allow element to be passed instead of text

Author: nolan

README.md

@@ -60,6 +60,12 @@ That's it, you're ready to go!
 Show a toast forever until you manually close it:
 ```javascript
  this.refs.toast.show('hello world!', DURATION.FOREVER);
+```
+
+Or pass an element:
+```javascript
+    this.refs.toast.show(<View><Text>hello world!</Text></View>);
+```
 
  // later on:
  this.refs.toast.close('hello world!');

README.zh.md

@@ -64,6 +64,10 @@
 
 在需要弹出提示框时使用上面代码即可。
 
+或者像这样
+```javascript
+    this.refs.toast.show(<View><Text>hello world!</Text></View>);
+```
 
 
 ### 用例  

index.js

@@ -108,7 +108,7 @@ export default class Toast extends Component {
                 <Animated.View
                     style={[styles.content, { opacity: this.state.opacityValue }, this.props.style]}
                 >
-                    <Text style={this.props.textStyle}>{this.state.text}</Text>
+                    {React.isValidElement(this.state.text) ? this.state.text : <Text style={this.props.textStyle}>{this.state.text}</Text>}
                 </Animated.View>
             </View> : null;
         return view;