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
