profiles: add a small tutorial for per-app

Signed-off-by: Blechd0se <alex.christ@hotmail.de>
Version 1.4.0

Signed-off-by: Blechd0se <alex.christ@hotmail.de>
shell: fix null pointer if there is no gpu file

This is a small hotfix for devices, which have no gpu path known
to aero control. Without this fix, Aero Control would just crash
instantly.

Signed-off-by: Blechd0se <alex.christ@hotmail.de>