This is a site.conf-breaking change in regard to the wireless config.
Make sure to read http://gluon.readthedocs.org/en/latest/user/site.html
and update your site.conf accordingly!

Support for 802.11s mesh interfaces has been added. Gluon now supports
three interface types: ap, ibss and mesh. All of them are now optional
and may be configured independently in site.conf.

A sample site.conf may look like this:

    wifi24 = {
            channel = 1,
            htmode = 'HT40+',
            ap = {
                    ssid = 'luebeck.freifunk.net',
            },
            ibss = {
                    ssid = '02:d1:11:37:fc:38',
                    bssid = '02:d1:11:37:fc:38',
                    mcast_rate = 12000,
            },
            mesh = {
                    id = 'ffhl-mesh',
                    mcast_rate = 12000,
            },
    },

see: http://gluon.readthedocs.org/en/latest/releases/v2014.3.html



Signed-off-by: Alexander Dahl <alex@netz39.de>

The file targets/$GLUON_TARGET/config becomes optional, as many targets
only used it to set the board and subtarget.

Also fix targets without subtarget.

Fixes #373

Fixes #347

This adds mesh_on_lan functionality.

A new optional site.conf option, mesh_on_lan, has been added. If set to
'true', all LAN ports will be used for meshing instead of being part of
the client bridge.