chore(graph/graph): remove dead code

This code was introduced with commented out sections. Just delete them.

Original commit: 18fc707fdf06aeb50fa5250f59f0ef4597d7cf73

Docker-DCO-1.1-Signed-off-by: Brandon Philips <brandon.philips@coreos.com> (github: philips)
block aufs on incompatible file systems

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
Merge pull request #6109 from unclejack/block_aufs_on_top_of_btrfs

block aufs on incompatible file systems
Merge pull request #5855 from philips/remove-dead-code

chore(graph/graph): remove dead code
Merge pull request #1 from dotcloud/master

Update from original