Tested-by: @RubenKelevra

gluon-status-page: API

This limits the number of concurrent users to 2 or 3 (approx. 4 connections per
user), greatly reducing DoS potential.

The TL-WR741ND will identify itself as a TL-WR740N/ND as well. This is fine as
the images are identical anyways.

Recent changes in the routing configuration of OpenWrt broke source address
selection, sometimes leading to the node trying to contact other addresses in
the mesh network from the next-node address.

Revert the problematic commits until this has been solved upstream.

The oldpackages repo has been dropped for Chaos Calmer.

gluon-announce, ...: don't output empty lists where not appropriate

Always output empty objects or nothing at all where objects are expected, but
no elements exist.

Also remove a few unneeded "requires", a few basic modules are provided by
announce.lua by default.

This updates batman-adv to 2015.0.

This also fixes the TL-WA830RE v1 model name.

Export Mode -> Expert Mode

final image name is shown as tp-link-tl-wa830re-v10

primary mac is the one printed on the case

Fixes #373

15 is the default in batman-adv-legacy, the new default 30 in newer batman-adv
versions is too high in larger networks.

docs/site-example: explain how to re-enter configmode