This patch is going to add the functionality of
setting snapshot state which OSC currently lacks.
Closes-Bug:#1535239
Change-Id: I2afd6567416e75ba0c70b73351cf1eb5394b3373
This change is inspired by the volume.py.
It allow the user to use openstack snapshot list --all.
Closes-Bug: #1517386
Change-Id: I72a53fcd0c5c5af539cd88b37e71b4331fa67473