Fixes #121

Based-on-patch-by: Tobias Hachmer <tobias@hachmer.de>

Config for rootfs and grub is not needed anymore (https://dev.openwrt.org/ticket/18074)

Config file not needed anymore (set implicitly by gluon now)

Avoid empty vars

Original patch by @MPW1412

Includes a profile for the NETGEAR WNDR3700v4 and WNDR4300v1

This still needs some work:

- there's no factory image causing `make images` to fail
- VoCore can not support BSS and IBSS at the same time
- multi-BSS mode (e.g. mesh + BSS) works if the macs only
  differ in the last 3 bits. Gluon expects to choose both MACs freely,
  though, so after flashing the image one should reset the wifi MACs.
  This is further complicated as VoCores have their MACs assigned
  without gaps making collisions likely.
- there are no buttons nor ethernet ports (without the dock, that is),
  so config-mode will not be possible as is

They can still be enabled by supplying BROKEN=1.