Radeon-tray service

Hi,

I found so usefull your program and I decided to add some feature because of my video card (hd 3470 with radeon driver, KMS). The program is mostly the same but now with a left click shows the status of the VGA and with the right click you can change the profiles.

I also added an installer for a service with systemd system that work from the computer startup for the tray icon and gave to it the possibility to change profiles without root privileges (uses zmq). 

If the program can't interact with the system or can't change the profiles it warn users with a message from the tray icon.

I hope that my changes may be useful, otherwise I have to thank you because now my laptop have a beautyful tray icon for the VGA.

PS: I see now that you added info about temperature and some minor changes, but I think that can be merged easily...

PPS: I added temp checker.