lvg module for managing LVM volume groups
various fixes in lvg module, added ability to reduce and extend VG, added Physical Extent parameter, added explicit creation of physical volumes
now using 'type=' for module parameters, replaced lambda with list comprehensions, simplyfied extend/reduce part of module, renamed dev parameter to pvs
Merge pull request #2357 from abulimov/lvg-module

lvg module for managing LVM volume groups