docs: add D-Link DIR-505 (A1) and Buffalo WZR-HP-G300NH (and remove WZR-HP-G300N, it is not actually supported)

Also
* create list of newly supported devices since v2015.1.2 in the v2015.2 release notes
* update information on docs/user/x86
* fix a comment in targets/ar71xx-generic/profiles.mk

This commit basically does two things: it urges users always to use an own
git repository to manage the site configuration, and it removed all
mentions of "communities" from the "Getting started" page, as it was too
Freifunk-specific.

Other documentation pages (especially the site configuration docs) should
probably be adjusted as well.

The Freifunk Münsterland firmware was formerly known as Freifunk Münster firmware - while the URL hasn't changed. In future, there will probably be subdomains with their own files, but for now this is state of the project.

`make modules` will generate a opkg repository containing kernel modules
matching the kernel of the Gluon images.

We'll soon have other output besides the images, having a single directory
for all output makes sense.

As the Gluon kernel won't be compatible with the OpenWrt upstream anymore,
we don't need the vermagic hack anymore.

I guess this is some copy and paste mistake which makes the example an
invalid site.conf. In my case merging the changes of the example into
our actual site.conf lead to an error because this line was merged to.

Fixes #376

Fixes #487

This package provides br-client and sets up a wireless AP interface for
clients.

gluon-radio-config contained only a single file. The code has been adjusted
to allow creating a Gluon configuration without WLAN support by removing
the wifi24 and wifi5 sections from site.conf.

The Gluon-specific functions of the gluon-simple-tc package are moved to
gluon-mesh-vpn-fastd.

The new options allow specifying custom repositories and are evaluated
in an upgrade script, not during build.

Fixes #401

Build requires Python 2 and libssl-dev