add sd-ext support

Change-Id: Ie3be4cb4fbdf87aad04d21f0ed1a9940314e418f
fstab: support ext4 and f2fs data and cache

Adapted from http://review.cyanogenmod.org/#/c/77234/

Change-Id: Ib91876ef7da852fb2b7b83f2da881af422fa5419