Start from existing X server (and without sudo)

[Jo-Blade]

I've made a fork based on the work of tangxinfa (https://github.com/tangxinfa/nvidia-xrun ;branch "fix-no-sudo") giving me the ability to run the nvidia-xrun script without admin rights, from existing X server. It should be used to create custom .desktop launcher, directly in the current X session. For the time, I tested it with gdm to create a new X session that can be launched from the session manager. I suppose the code can be improve (I'm still a beginner).

Sincerely (sorry for my bad English, I'm a french student)