Update desktop_nasa.py

SET XFCE WALLPAPER
Update desktop_nasa.py

Desktop environment options, XFCE settings, Images resolution in the folder name, Also a clean image is saved if I chose to use image with text
Update desktop_nasa.py

GET_IMAGE_ONLY = False
Merge pull request #2 from FabioTrevisiol/master

if you like these changes, maybe you can merge it