logger.js: Remove Winston dependancy and replace by custom logger

This is done to avoid grabbing a bunch of dependencies and have a slimer
distribution

Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>
iotkit-agent.service: make service file more generic and change fail timeout to 10s

Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>