Add an index column to 'nova list'

Registered by wingwj

Now 'nova list' only shows the 'ID'/'Name'/'Status'/'Task State'/'Power State'/'Networks' columns. That's OK for normal using.

But if you have more than 200 VMs or even larger in one environment,
'nova list' will print out lots of lines even if I add some filters (such as '--name'/'--status'/..).

It's very hard to count the amount of them.
Like this: http://paste.openstack.org/show/60553/

I just have to use 'nova list |wc' to count them (minus 4 line)..

So, if an index column add to 'nova list',
it can easily give the amount of the VMs under filtering opinions('--name'/'--status'/..).

Blueprint information

Status:
Not started
Approver:
None
Priority:
Undefined
Drafter:
wingwj
Direction:
Needs approval
Assignee:
wingwj
Definition:
New
Series goal:
None
Implementation:
Unknown
Milestone target:
None

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Sprints

Whiteboard

Addressed by: https://review.openstack.org/89468
    Add an index column to 'nova list'

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