feature add xfs online resizing support
Merge pull request #40 from sgzijl/feature-add_xfs_online_resize

xfs online resizing support
Ensure README complies with style guide

Without this patch, the README propagates incorrect style.
Merge pull request #41 from ghoneycutt/style

Ensure README complies with style guide
Allow for physical_volumes and volume_groups that change as system lives
Remove spec test that does not work
Merge pull request #30 from csschwe/createonly-for-vg-pv

Allow for physical_volumes and volume_groups that change a system lives
Use fully qualified volume paths
Implement 'instances' method for all LVM resources

This method makes it possible to use constructs like:
  resources { 'physical_volume': purge => true, noop => true, }
  resources { 'logical_volume':  purge => true, noop => true, }
  resources { 'volume_group':    purge => true, noop => true, }
Implement empty 'extents' method

It is required by 'instances' method.
There is no simple way to get LV size in extents,
so leave it empty for now.
Set default LV unit size to MB