Support for Pi3 and general update
- Added explicit support for Raspberry Pi 3,
- fixed #4,
- updated dependencies and code to be up to date with current version of Ansible,
- made Python code compatible with both Python 2 and 3,
- fixed (again, hopefully right this time) the reboot handler to correctly wait and respond to reboot after reconfiguration.
Thanks to @colin-nolan for contributing and @lupin-de-mid for reporting #4.