storage: Track successful creation of LV for removal
    
    https://bugzilla.redhat.com/show_bug.cgi?id=1233003
    
    Track when the logical volume was successfully created in order to
    properly handle the call to virStorageBackendLogicalDeleteVol. It's
    possible that the failure to create was because someone created an
    LV in the pool outside of libvirt's knowledge. In this case, we don't
    want to delete that LV.  A subsequent or future refresh of the pool
    will find the volume and cause an earlier failure
    
    Signed-off-by: John Ferlan <jferlan@redhat.com>