Include a pvremove module and pvabsent state

This is usefull for ensuring that the block device is removed from all
kernel memory.  This is required for detaching vdb's in xen.
Fix the logic ordering of pv_absent
check device names for physical volumes
fix git.py state pylint problems
Merge pull request #12690 from gtmanfred/develop

Include a pvremove module and pvabsent state