- changed minimum sdk version to 14
- created HttpDeleteWithBody subclass of HttpEntityEnclosingRequestBase
  to represent an HTTP DELETE request with payload(json or other)
- created new public void delete(Context context, String url, HttpEntity
  entity, String contentType, AsyncHttpResponseHandler responseHandler)
  method in AsyncHttpClient to send DELETE request with additional
  payload the same way as #post(Context context, String url, HttpEntity
  entity, String contentType, AsyncHttpResponseHandler responseHandler)
  does