Response string charset option

The XML response of the web service I need is encoded in ISO-8859-1. There was no way for me to correct this since UTF-8 is hardcoded for the response string.

I simply added a class variable for the charset to the AsyncHttpResponseHandler. The default is still UTF-8, but now there's an option to set the charset via a setter. I did not add another constructor (yet?) to keep it simple.