init-ifupdown: fix recipe
images: Add images and packagegroup

Add image recipes to make building a Wandboard AP easier:
- wandboard-ap-image-base: Image based on core-image-base that includes the
  correct firmware for the BCM4329, hostapd, dhcp-server, and wpa-supplicant.
- wandboard-ap-image-test: Same as the base image with some test utilities
  added.