This will ensure that gluon-site and gluon-autoupdater are rebuilt
correctly when GLUON_RELEASE or GLUON_BRANCH change.

The size of the factory images is limited to 4MB, which caused build
failures when many additional packages were included.

Rather than moving the device to ar71xx-tiny, we ignore the factory images
and just build the sysupgrade. This way, the whole flash is usable for
Gluon.

This means that installing Gluon on these devices will now require to flash
a plain LEDE image first, and then upgrading using the Gluon sysupgrade
image.

Fixes #1020

rpcd is not included in our images anymore since switching to gluon-web, so
we don't need to disable it anymore.

This makes the LAN port the PoE master, so the AirGateway can be used to
supply power to another node connected via mesh-on-LAN.

Fixes #608

We always want to prefer the unique node address for outgoing traffic. Note
that this doesn't have an effect with batman-adv, as usually br-client will
be the outgoing interface, so the unique address would be chosen anyways.

This was introduced in ffhh-packages at https://github.com/freifunkhamburg/ffhh-packages/tree/master/gluon-config-mode-reboot-ffhh

Make use of our new _translate() function.

_translate() will return nil when no match is found.

The gluon-web package is basically a stripped-down and refactored version
of the LuCI base.

As convenient as the Map is, the underlying code is very complex and will
be removed.

To fix the autoupdater.

Add translation support to gluon-status-page, including English, German and Russian translations.

`make list-targets` can be used to discover the available targets in
scripts.

Fixes #1043

In preparation for Babel support.