aUniSync 0.2.1: minor improvements for GNOME

A very minor point release improving the feel of the app in GNOME 3.

aUniSync 0.2.0: error notifications

First public release. In addition to the usual system tray behaviour, aUniSync now shows desktop notifications for failing profiles, with buttons for retrying, or launching the Unison GUI to investigate the conflict.

The tool now requires Python 3.x during setup, and at runtime.