Demandshaper service should follow the convention of symlinking service file

[borpin]

demandshaper/install.sh

Line 19 in e23c97e

sudo cp $DIR/$service.service /lib/systemd/system

Instead of copying the file, demandshaper should follow the convention of symlinking the service file from the installed folder.

The EXEC path then does not need to be set.

[borpin]

This should really be fixed.