wan: implement basic infrastructure for com.palm.wan service

Open-WebOS-DCO-1.0-Signed-Off-By: Simon Busch <morphis@gravedo.de>
Rework driver registration functionality to be service instance independent

Open-WebOS-DCO-1.0-Signed-Off-By: Simon Busch <morphis@gravedo.de>
Install log handler as early as possible

Open-WebOS-DCO-1.0-Signed-Off-By: Simon Busch <morphis@gravedo.de>
Move driver implementations out of global source directory

Open-WebOS-DCO-1.0-Signed-Off-By: Simon Busch <morphis@gravedo.de>
ofono: implement a wan driver

Open-WebOS-DCO-1.0-Signed-Off-By: Simon Busch <morphis@gravedo.de>