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.

salt/modules/linux_lvm.py

@@ -202,6 +202,23 @@ def pvcreate(devices, **kwargs):
     return out[0]
 
 
+def pvremove(devices):
+    '''
+    Remove a physical device being used as an LVM physical volume
+
+    CLI Examples:
+
+    .. code-block:: bash
+
+        salt mymachine lvm.pvremove /dev/sdb1,/dev/sdb2
+    '''
+    cmd = 'pvremove -y'
+    for device in devices.split(','):
+        cmd += ' {0}'.format(device)
+    out = __salt__['cmd.run'](cmd).splitlines()
+    return out[0]
+
+
 def vgcreate(vgname, devices, **kwargs):
     '''
     Create an LVM volume group

salt/states/lvm.py

@@ -69,6 +69,36 @@ def pv_present(name, **kwargs):
     return ret
 
 
+def pv_absent(name):
+    '''
+    Ensure that a Physical Device is not being used by lvm
+
+    name
+        The device name to initialize.
+    '''
+    ret = {'changes': {},
+           'comment': '',
+           'name': name,
+           'result': True}
+
+    if not __salt__['lvm.pvdisplay'](name):
+        ret['comment'] = 'Physical Volume {0} does not exist'.format(name)
+    elif __opts__['test']:
+        ret['comment'] = 'Physical Volume {0} is set to be removed'.format(name)
+        ret['result'] = None
+        return ret
+    else:
+        changes = __salt__['lvm.pvremove'](name)
+
+        if not __salt__['lvm.pvdisplay'](name):
+            ret['comment'] = 'Failed to remove Physical Volume {0}'.format(name)
+            ret['result'] = False
+        else:
+            ret['comment'] = 'Removed Physical Volume {0}'.format(name)
+            ret['changes'] = changes
+    return ret
+
+
 def vg_present(name, devices=None, **kwargs):
     '''
     Create an LVM volume group