network: fix active connection state sync issue again

Add custom dbus watcher to catch all active connection
PropertiesChanged signals. And refactor code for such
work.

tower: https://tower.im/projects/8f19f0bf0e754f0b82ef2c24bc230973/todos/c82b9fd4b1d648f7abb579222baeccf3/
tower: https://tower.im/projects/8f19f0bf0e754f0b82ef2c24bc230973/todos/5c9cf29f29f4466e8edd1efba286a237/
Change-Id: I7a35290e01d2b21f6199a8825df648b515aed19e