applet: initialize permissions in the applet to show 'Enable ...' menu items'...

applet: initialize permissions in the applet to show 'Enable ...' menu items' visibility correctly (rh #627365)

'Enable Networking/Wireless/Mobile Broadband' was grayed out due to not
initializing permissions. The first 'permission-changed' signals are emitted
from withing NMClient constructor and the signal handler is not connected yet.
So we call nm_client_get_permission_result() to set initial permissions.