cli: fix deactivation for multiple connections (bgo #740775) (rh #1168383)

$ nmcli connection down aa bb cc

It has been broken by commit 20566c76de0d18162af020852ae1e2055addcfff.

Fixups by dcbw.

https://bugzilla.gnome.org/show_bug.cgi?id=740775
https://bugzilla.redhat.com/show_bug.cgi?id=1168383
cli: additional fix for nmcli connection down

nmcli crashed when a timeout was hit, because 'info' was used after freeing
in down_timeout_cb().

Fixes 4a7c88621ddd8e8089f63071e3114003a0efc622.
contrib/rpm: ignore libgsystem/ repository in build_clean.sh
device: don't disconnect assumed connections

Transition them to activated status when they fail.

https://bugzilla.redhat.com/show_bug.cgi?id=1141264
device: don't fail assumed connections when IP config is unavailable

Progress the to check-ip with whatever configuration that is available.

https://bugzilla.redhat.com/show_bug.cgi?id=1141264
cli: g_strdup(NULL) returns NULL; simplify code for that
ifcfg-rh: don't include nm-utils-private.h outside of libnm-core/
devices: don't release slaves on exit (rh #1169936)

nm_device_removed() calls nm_device_release_one_slave() in order to
fix up NetworkManager's master/slave bookkeeping, but we don't want to
tell the kernel to actually unslave the device, since that would
happen automatically anyway if the device was really removed, and
shouldn't happen if the device is just being removed from NM's device
list.

(In particular, don't remove all libvirt-created virtual network
devices from virbr0 when NetworkManager exits.)
core: fix leak of generated connection if device is active

Don't generate (and add to settings) a connection if we aren't going
to use it anyway.
libnm-core: fix the rule for parsing 'gateway' out of 'addresses' (rh #1170199)

We were always using the gateway field of the first address in
ipv4.addresses / ipv6.addresses to set the gateway, but to be
compatible with old behavior, we should actually be using the first
non-0 gateway field (if the first one is 0).
Merge remote-tracking branches 'fd/lr/ipv6-tokens', 'fd/lr/veth-managed', 'fd/lr/no-udev', 'fd/lr/vpn-fixes' and 'fd/lr/assumed-activation-rh1141264' into integration