SRD channels are only 25 mW and hence have short range, this is rarely
what users want.

It's not supported by many clients, thus disable for now.

Exchange the signing key used by the CI/CD pipeline with a new key.

allow the SSID to change to the offline SSID once every 15 minutes

In non multi domain setups, vxlan is mandatory.

Release notes cites:
--- snip ---
In single domain setups, the new mesh.vxlan option is mandatory. It
should be set to true in new meshes; existing setups should set it to
false to retain compatibility with older versions of Gluon.
--- snap ---

It seems that we do have to wait until all Nodes are upgraded to
v2018.1, so we set it to false by now.

remove ibss

remove ibss mesh

+ update ffs-watchdog
+ update mesh ssid

The htmode option has been dropped, the channel width is now always set to 20MHz (https://github.com/freifunk-gluon/gluon/issues/487).