session-daemon: fix dde-session-daemon high cpu issue

Caused by an issue of network module, dbus connection
may be closed if IsDeviceEnabled() is called when
initializing.

And also adjust code order to ensure dbus.Wait()
executed before initializing modules, so that
dde-session-daemon will exited and restart nomally
if any dbus error occured.

tower: https://tower.im/projects/8f19f0bf0e754f0b82ef2c24bc230973/todos/5e26d05f489548858edc4e77c79c411d/#e339f0d9b44d4e6eb7ff6824a1b080ff
Change-Id: Iac8e533a7e65fb8d648fa9493cbaef3e88f166c7