Add sdcard support for recovery mode

Add tool mk_updatepackage4sdcard to generate sdcard update package.
Change the name and size of android rootfs ext4 image.
Add recovery.fstab for sdcard.

Signed-off-by: Max Liao <liaops@embedinfo.com>
relese: a better way to copy data

we copy the data directory instead of all the files in it.

Signed-off-by: Royce Jiang <jiangxd@embedinfo.com>