Issue #12: Handling multiple notifications on Android devices

## Quick Example

```

```javascript

    var push = PushNotification.init({ "android": {"senderID": "12345679"},

    	 "ios": {}, "wp": {"channelName": "12345679"} } );

Parameter | Description

--------- | ------------

`options` | `JSON Object` platform specific initialization options.

`options.android` | `JSON Object` Android specific initialization options.

`options.android.senderID` | `String` Maps to the project number in the Google Developer Console.

`options.ios` | `JSON Object` iOS specific initialization options.

`options.wp` | `JSON Object` Windows specific initialization options.

`options.wp.channelName` | `String` Channel URI from Microsoft.

#### Returns

push.setApplicationIconBadgeNumber(successHandler, errorHandler, count);

```

## Android Behaviour

By default when using this plugin on Android each notification that your app receives will replace the previous notification in the shade. 

If you want to see multiple notifications in the shade you will need to provide a notification ID as part of the push data sent to the app. For instance if you send:

```

{ 

  title: "Test Push",

  message: "Push number 1"

}

```

Followed by:

```

{ 

  title: "Test Push",

  message: "Push number 2"

}

```

You will only see "Push number 2" in the shade. However, if you send:

```

{ 

  title: "Test Push",

  message: "Push number 1",

  nodId: 1

}

```

and:

```

{ 

  title: "Test Push",

  message: "Push number 2",

  nodId: 2

}

```

You will only see both "Push number 1" and "Push number 2" in the shade.

## Native Requirements

- There should be no dependency on any other plugins.