Setup instructions in README.md outdated

[danielhoop]

Thanks a lot for this module!
I just wanted to inform you that one step of the process to integrate the module in an app (described in README.md) is outdated.
Erroneous part after: "Register module in MainActivity.java"

...
Block that describes changes to public class MainActivity extends ReactActivity
...

According to the React Native Documentation it should be done like this:
In MainApplication.java ...

import com.xeodou.rctplayer.*;  // <--- import
...
@Override
    protected List<ReactPackage> getPackages() {
      return Arrays.<ReactPackage>asList(
          new MainReactPackage(),
	  new ReactPlayerManager()  // <--- insert
      );
    }
...