Check for container operation in iamge_upload
Check for container operation in iamge_upload

Previous versions of LXD (below 0.22) does not send
an operation id. So check to see if we have an operation id
before waiting for the image upload to finish.

Signed-off-by: Chuck Short <753a8074f04ffd62a8fff7516e3ae689be8e35ad@canonical.com>

tpouyer/nova-lxd,tpouyer/nova-lxd