Add in a global lock around pool refresh.
Add in a global lock around pool refresh.

This ensures that we don't try to refresh a pool that
is currently having a volume created on it, which
libvirt does not allow.

Signed-off-by: Chris Lalancette <281cd07d7578d97c83271fbbf2faddb83ab3791c@gmail.com>

ndonegan/oz,moofrank/oz,NeilBryant/oz,clalancette/oz,imcleod/oz,moofrank/oz,NeilBryant/oz,cernops/oz,nullr0ute/oz,clalancette/oz,nullr0ute/oz,mgagne/oz,ndonegan/oz,mgagne/oz,imcleod/oz,cernops/oz