Feature/themes and rqdata

[CAMOBAP]

• Support setData, execute() args passthrough #10

Open questions

• I suppose that custom=false param in URL will be handled correctly
• react-native-webview has really poor error handling. In case of malformed HTML onError not triggered. Probably because of this we don't have it at all. But it will be really useful to get some errors in onMessage. I have tried this:

  <WebView
   ...
   onError={(event) => {
      event.nativeEvent.data = 'error';
      onMessage(event);
    }}
   ...
  />
  

[CAMOBAP]

@e271828- both rqdata and theme arguments implemented and ready for review.