Modified library to work with GoogleAppEngine

This will allow for the current android library to work on GoogleAppEngine - I have made two major change:
1. I have replaced the HTTPClient methods from org.apache with the java.net HTTPUrlConnection methods. 
2. Any java.awt images methods were replaced by the Images API methods of GoogleAppEngine.
I removed the override as the post method which uses the HTTPClient (HTTPPost) is no longer defined in the interface RequestHandler. It has become an optional method.