This patch completely separates supplicant's code from dbus.
It introduces three new notifications which copes with all
remaining dbus stuff.
wpas_notify_unregister_interface() was renamed to
wpas_notify_iface_removed().
This introduces a new mechanism for collecting notification calls into
a single place (notify.c). As a result of this, most of the
wpa_supplicant code does not need to know about dbus (etc. mechanisms
that could use the notifications). Some empty placeholder functions are
also added in preparation of new dbus code that needs more event
notifications.
