When a volume has no name, it now shows the
ID instead. I also added a fixture data that
represents such a volume being in the system.
Fixes bug #1012380
You can also now use truncate=i on DataTable
Columns in order to have the value truncated if
it goes beyond i characters.
On top of this I fixed/made-clearer a bunch of
the tests relating to volumes and instances.
Please do NOT use deepcopy() of fixture data
in tests any more, instead just create a new
fixture for the data you want.
Change-Id: If2f92b5d04b04f08f5cacca03f614fce5ea38702
c17b06d08a