use exec to launch app
use exec to launch app

so signals from ``docker stop`` get forwarded to the process
Branlala/docker-sickbeardfr,Branlala/docker-sickbeardfr,Branlala/docker-sickbeardfr,nunofgs/rpi-sickbeard,Branlala/docker-sickbeardfr,Branlala/docker-sickbeardfr,timhaak/docker-sickbeard