Shows the module apk size. Fixes #243

All you need to do is add the property size to the xml file on your server.
Rovo89 said that size value would be in bytes. And please export string to strings.xml file.

<string name="download_view_size">Size: %1$,d kB</string>

String moduleSize = String.format(getString(R.string.download_view_size), item.size/1024);
holder.txtSize.setText(moduleSize);