dispatcher: introduce new env variables for gateway address (bgo #740363)

IP4_GATEWAY
VPN_IP4_GATEWAY
IP6_GATEWAY
VPN_IP6_GATEWAY

We still put gateway into IP[46]_ADDRESS_N for backward compatibility.

https://bugzilla.gnome.org/show_bug.cgi?id=740363
man: update version reference to 1.0 in manual pages
man: fix formatting leftover from man -> xml migration
cli: Watch for device as well as AC state changes when activating

The signals might be delivered in no particular order and we need to wait for
the device to reach stable state (whether it's successfully conntected or not)
as well as the active connection to leave ACTIVATING state.

https://bugzilla.gnome.org/show_bug.cgi?id=740320
core: minor fix to ensure safe boolean comparison in have_ip6_address()

Signed-off-by: Thomas Haller <thaller@redhat.com>