I have created 2 Fedora 21 images for the HummingBoard and Cubox-i.

http://vps1.mkreder.com/Fedora-Mate-armhfp-21-5-sda.raw.xz
MATE

http://vps1.mkreder.com/Fedora-LXDE-armhfp-21-5-sda.raw.xz
LXDE

I will create a XFCE based image too, soon.
In order to extend the root filesystem on this image, you need to run:

fdisk /dev/location-of-your-fedora-arm-media << EOF
d
3
n
p

2001954

w
EOF
partprobe /dev/location-of-your-fedora-arm-media
e2fsck -f /dev/location-of-your-fedora-arm-media3
resize2fs /dev/location-of-your-fedora-arm-media3

More information about Fedora on these boards can be found on this github page