Message registration and arrival

https://github.com/urbanairship/urbanairship-cordova/issues/337

Do we need this?

```
        <service android:name="com.rmm.test.app.PushService" >
            <intent-filter android:priority="10" >
                <action android:name="com.google.firebase.MESSAGING_EVENT" />
            </intent-filter>
        </service>
```
