How can I connect my Nokia Lumia 520 with Ubuntu 14.04?

The author of this project: Android File Transfer For Linux luckily for me agreed to add WP8 support and now this is the only solution that reliable works, afaik.
Now it's able to connect my Lumia 1020 WP8.1 Denim and Kubuntu 15.04 via usb.

Of course, device shall be unlocked with correct PIN beforehand.

The project is a library and has simple GUI which is mostly for library demonstration and testing purposes, so don't blame it for UX.