Create volume snapshot CRDs

Version Control Information

Source branch: fix/create-volume-snapshot-crds
Target branch: devel

Commits:

* Create volume snapshot CRDs

Creating volume snapshots requieres volume snapshot CRDS and a
snapshot controller which where missing and are now deployed.
Tests for creating and rehydrating snapshots with cinder CSI
are also added.

Fixes #549.

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Description

PVs rehydrated from snapshots need to be deleted, before the corresponding snapshot can be deleted. That's why during testing the rehydrated PV is deleted before the namespace to make sure the condition is met. There is no error message if a snapshot or PV could not be deleted successfully.

Closes: #549 (closed)

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