just made a auto expand root fs os v0.4 img, it will expand the partition to be full size of sdcard
I hope it will help a little.
https://mega.nz/#F!IUkxQSjB!d_H9leVSSl6tDP4X0oWnag
this image will reboot twice while the first boot,then everything will be all right.
tested on 16GB TF card