As you may know, Urban Lightscape is an open source application (and Photoshop plugin) for applying corrections to photos, including brightness adjustments, dodging and burning and synthetic lighting.
The latest version available is Urban Lightscape 1.4.0, which has been released a while ago, coming with some fixes for some already known bugs.
The latest versions of UrbanLightscape are available via some third party PPA, so you should not encounter too many problems when installing the software on Ubuntu systems.
All you need to do is add the PPA to your system, update the local repository index and install the urbanlightscape package:
$ sudo add-apt-repository ppa:dhor/myway
$ sudo apt-get update
$ sudo apt-get install urbanlightscape
Optional, to remove urbanlightscape, do:
$ sudo apt-get remove urbanlightscape
The installation instructions should work on Ubuntu 15.10 Wily Werewolf, Ubuntu 15.04 Vivid Vervet, Ubuntu 14.04 Trusty Tahr, Linux Mint 17.x, Elementary OS 0.3 Freya and other Ubuntu derivative systems.