ar71xx: add support for the Ubiquiti UniFi AP-Outdoor device

[juhosg:
  - rename and refresh 660-MIPS-ath79-ubnt-xm-add-unifi-outdoor patches
  - wrap long lines in mach-ubnt-xm
  - remove default network config, set it from uci-defaults/network
    instead
  - remove user-space, and image generation stuff]

Signed-off-by: Daniel Dickinson <daniel@powercloudsystems.com>
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

SVN-Revision: 34196