Add devices/data_alignment_detection to lvm.conf.

Add devices/data_alignment_detection to lvm.conf.

Adds 'data_alignment_detection' config option to the devices section of
lvm.conf.  If your kernel provides topology information in sysfs (linux
>= 2.6.31) for the Physical Volume, the start of data area will be
aligned on a multiple of the ’minimum_io_size’ or ’optimal_io_size’
exposed in sysfs.

minimum_io_size is used if optimal_io_size is undefined (0).  If both
md_chunk_alignment and data_alignment_detection are enabled the result
of data_alignment_detection is used.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>