Initial working implementation of lvm

Note that the block mapping needs to be set properly via aws_ebs_vols in
Bindle to attach all ephemeral devices to /dev/sdX. Then AWS will
arbitrarily rename them to /dev/xvdX for you, it is these that need to
be set for the lvm_white_list parameter
Properly disable lvm
Merge pull request #2 from SeqWare/feature/lvm

Feature/lvm