https://bugzilla.redhat.com/show_bug.cgi?id=1072653

Upon successful upload of a volume, the target volume and storage pool
were not updated to reflect any changes as a result of the upload. Make
use of the existing stream close callback mechanism to force a backend
pool refresh to occur in a separate thread once the stream closes. The
separate thread should avoid potential deadlocks if the refresh needed
to wait on some event from the event loop which is used to perform
the stream callback.