sdcard: Support sdcardfs

Add ability to use sdcardfs if kernel support is found.
In the future, we will likely remove the fuse components
entirely, but for now, just use sdcardfs when possible.

Bug: 19160983
Change-Id: I35e4d6cb5976c00c6f87ff7fc478ba9f9d212c05
Signed-off-by: Daniel Rosenberg <drosen@google.com>