v1.0.3: Support Gotham (drops support for old versions, Frodo or newer required)

- Bump Python API to 2.1.0 (which means Frodo or newer).
- Update the changelog

I haven't found any issues with configuring the controller after these minimal changes. Tested under Arch Linux 64-bit with build from xbmc master (xbmc/xbmc@56394a41e78e41a79f121fcf8da1eeae15739d1e).