Backport of r47591 and r48427

Should be redundant after 0bd0df6f

Signed-off-by: Felix Kaechele <felix@kaechele.ca>

Change the limit to match our recommendation in the site-example.

We're too close to the release of Gluon 2016.1 to do a full update of our
OpenWrt tree, therefore just make a backport of this.

Fixes #558

Restrict to link-local addresses to prevent amplification attacks from
outside the mesh, or such attacks affecting the outside world.

Fixes #637

Fixes #574

docs: Corrected some typos and strange grammar

If the query was via multicast, the response isn't matched by
--state ESTABLISHED,RELATED

This fixes #619

Instead of starting gluon-respondd from a hotplug handler, add a proper
init script. The new init script has a restart_if_running argument which
is now used by the hotplug handler.

gluon-announced and gluon-announce are merged to gluon-respondd.

Added Support for TP-Link WR843ND

Tests done to verify that this worked as intended:
 * checked plattform_info image_name
 * checked primary_mac
 * does appear in ffmap-d3
 * does mesh
 * does fastd-VPN

Also remove the BROKEN check as the UniFi Outdoor Plus support seems to
work fine now.

Fixes #272

add support for ubiquiti airRouter

docs: Update autoupdater.rst