Massive fixup of libnm-glib to:
	a) have all objects (with the exception of VPN) cache their properties and
		update them asynchronously on PropertiesChanged signals from NM
	b) return internal const data for most attributes/properties instead of
		allocated values that the caller must free
	c) cache wrapped objects such that a given D-Bus path will always map to the
		same GObject returned by libnm-glib
	d) remove a few signals and move them to GObject property notifications
	e) match recent NM D-Bus API changes for activation/deactivation
	f) remove some private functions from libnm-glib headers



git-svn-id: http://svn-archive.gnome.org/svn/NetworkManager/trunk@3491 4912f4e0-d625-0410-9fb7-b9a5a253dbdc