Patch #1 needs some fixups, namely:
1) fix the D-Bus property documentation, and mention that the value is
absolute in CLOCK_BOOTTIME seconds, so CLOCK_BOOTTIME seconds -
last_seen = seconds ago the AP was last seen
2) make the property a u32 (it'll never be negative)
3) same thing for libnm-glib, a u32, and update the code documentation
to talk about CLOCK_BOOTTIME etc
4) for nm-wifi-ap.c, keep the current 'gint' stuff for
nm_ap_set_last_seen(), but in get_property() convert last_seen into
BOOTTIME units with nm_utils_monotonic_timestamp_as_boottime() from
Thomas' patch so that D-Bus clients see BOOTTIME, and add a code comment
about this in get_property()
Sound OK?